[PATCH v5 0/7] Fixes integer overflow or integer truncation issues in page lookups, ttm place configuration and scatterlist creation

[PATCH v5 0/7] Fixes integer overflow or integer truncation issues in page lookups, ttm place configuration and scatterlist creation

[Gwan-gyeong Mun]

This patch series fixes integer overflow or integer truncation issues in
page lookups, ttm place configuration and scatterlist creation, etc.
We need to check that we avoid integer overflows when looking up a page,
and so fix all the instances where we have mistakenly used a plain integer
instead of a more suitable long.
And there is an impedance mismatch between the scatterlist API using
unsigned int and our memory/page accounting in unsigned long. That is we
may try to create a scatterlist for a large object that overflows returning
a small table into which we try to fit very many pages. As the object size
is under the control of userspace, we have to be prudent and catch the
conversion errors. To catch the implicit truncation as we switch from
unsigned long into the scatterlist's unsigned int, we use our overflows_type
check and report E2BIG prior to the operation. This is already used in
our create ioctls to indicate if the uABI request is simply too large for
the backing store. 
And ttm place also has the same problem with scatterlist creation,
and we fix the integer truncation problem with the way approached by
scatterlist creation.
And It corrects the error code to return -E2BIG when creating gem objects
using ttm or shmem, if the size is too large in each case.
In order to provide a common macro, it moves and adds a few utility macros into drm util header

v5: Fix an alignment to match open parenthesis
    Fix macros to be enclosed in parentheses for complex values
    Fix too long line warning
v4: Fix build warnins that reported by kernel test robot. (kernel test robot <lkp@intel.com>)
    Add kernel-doc markups to the kAPI functions and macros (Mauoro)
v3: Modify overflows_type() macro to consider signed data types and
	add is_type_unsigned() macro (Mauro)
    Make not use the same macro name on a function. (Mauro)
    For kernel-doc, macros and functions are handled in the same namespace,
    the same macro name on a function prevents ever adding documentation for it.
    Not to change execution inside a macro. (Mauro)
    Fix the problem that safe_conversion() macro always returns true (G.G)
    Add safe_conversion_gem_bug_on() macro and remove temporal SAFE_CONVERSION() macro. (G.G.)

Chris Wilson (3):
  drm/i915/gem: Typecheck page lookups
  drm/i915: Check for integer truncation on scatterlist creation
  drm/i915: Remove truncation warning for large objects

Gwan-gyeong Mun (4):
  drm: Move and add a few utility macros into drm util header
  drm/i915: Check for integer truncation on the configuration of ttm
    place
  drm/i915: Check if the size is too big while creating shmem file
  drm/i915: Use error code as -E2BIG when the size of gem ttm object is
    too large

 drivers/gpu/drm/i915/gem/i915_gem_internal.c  |   6 +-
 drivers/gpu/drm/i915/gem/i915_gem_object.c    |   7 +-
 drivers/gpu/drm/i915/gem/i915_gem_object.h    | 303 +++++++++++++++---
 drivers/gpu/drm/i915/gem/i915_gem_pages.c     |  27 +-
 drivers/gpu/drm/i915/gem/i915_gem_phys.c      |   4 +
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c     |  19 +-
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c       |  23 +-
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c   |   5 +-
 .../drm/i915/gem/selftests/i915_gem_context.c |  12 +-
 .../drm/i915/gem/selftests/i915_gem_mman.c    |   8 +-
 .../drm/i915/gem/selftests/i915_gem_object.c  |   8 +-
 drivers/gpu/drm/i915/gvt/dmabuf.c             |   9 +-
 drivers/gpu/drm/i915/i915_gem.c               |  18 +-
 drivers/gpu/drm/i915/i915_gem.h               |   4 +
 drivers/gpu/drm/i915/i915_scatterlist.h       |  11 +
 drivers/gpu/drm/i915/i915_utils.h             |   5 +-
 drivers/gpu/drm/i915/i915_vma.c               |   8 +-
 drivers/gpu/drm/i915/intel_region_ttm.c       |  20 +-
 include/drm/drm_util.h                        |  77 +++++
 19 files changed, 481 insertions(+), 93 deletions(-)

-- 
2.34.1

[PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Gwan-gyeong Mun]

It moves overflows_type utility macro into drm util header from i915_utils
header. The overflows_type can be used to catch the truncation between data
types. And it adds safe_conversion() macro which performs a type conversion
(cast) of an source value into a new variable, checking that the
destination is large enough to hold the source value.
And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
while compiling.

v3: Add is_type_unsigned() macro (Mauro)
    Modify overflows_type() macro to consider signed data types (Mauro)
    Fix the problem that safe_conversion() macro always returns true
v4: Fix kernel-doc markups

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/gpu/drm/i915/i915_utils.h |  5 +-
 include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index c10d68cdc3ca..345e5b2dc1cd 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -32,6 +32,7 @@
 #include <linux/types.h>
 #include <linux/workqueue.h>
 #include <linux/sched/clock.h>
+#include <drm/drm_util.h>
 
 #ifdef CONFIG_X86
 #include <asm/hypervisor.h>
@@ -111,10 +112,6 @@ bool i915_error_injected(void);
 #define range_overflows_end_t(type, start, size, max) \
 	range_overflows_end((type)(start), (type)(size), (type)(max))
 
-/* Note we don't consider signbits :| */
-#define overflows_type(x, T) \
-	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))
-
 #define ptr_mask_bits(ptr, n) ({					\
 	unsigned long __v = (unsigned long)(ptr);			\
 	(typeof(ptr))(__v & -BIT(n));					\
diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h
index 79952d8c4bba..1de9ee5704fa 100644
--- a/include/drm/drm_util.h
+++ b/include/drm/drm_util.h
@@ -62,6 +62,83 @@
  */
 #define for_each_if(condition) if (!(condition)) {} else
 
+/**
+ * is_type_unsigned - helper for checking data type which is an unsigned data
+ * type or not
+ * @x: The data type to check
+ *
+ * Returns:
+ * True if the data type is an unsigned data type, false otherwise.
+ */
+#define is_type_unsigned(x) ((typeof(x))-1 >= (typeof(x))0)
+
+/**
+ * overflows_type - helper for checking the truncation between data types
+ * @x: Source for overflow type comparison
+ * @T: Destination for overflow type comparison
+ *
+ * It compares the values and size of each data type between the first and
+ * second argument to check whether truncation can occur when assigning the
+ * first argument to the variable of the second argument.
+ * Source and Destination can be used with or without sign bit.
+ * Composite data structures such as union and structure are not considered.
+ * Enum data types are not considered.
+ * Floating point data types are not considered.
+ *
+ * Returns:
+ * True if truncation can occur, false otherwise.
+ */
+
+#define overflows_type(x, T) \
+	(is_type_unsigned(x) ? \
+		is_type_unsigned(T) ? \
+			(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
+			: (sizeof(x) >= sizeof(T) && (x) >> (BITS_PER_TYPE(T) - 1)) ? 1 : 0 \
+	: is_type_unsigned(T) ? \
+		((x) < 0) ? 1 : (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
+		: (sizeof(x) > sizeof(T)) ? \
+			((x) < 0) ? (((x) * -1) >> BITS_PER_TYPE(T)) ? 1 : 0 \
+				: ((x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
+			: 0)
+
+/**
+ * exact_type - break compile if source type and destination value's type are
+ * not the same
+ * @T: Source type
+ * @n: Destination value
+ *
+ * It is a helper macro for a poor man's -Wconversion: only allow variables of
+ * an exact type. It determines whether the source type and destination value's
+ * type are the same while compiling, and it breaks compile if two types are
+ * not the same
+ */
+#define exact_type(T, n) \
+	BUILD_BUG_ON(!__builtin_constant_p(n) && !__builtin_types_compatible_p(T, typeof(n)))
+
+/**
+ * exactly_pgoff_t - helper to check if the type of a value is pgoff_t
+ * @n: value to compare pgoff_t type
+ *
+ * It breaks compile if the argument value's type is not pgoff_t type.
+ */
+#define exactly_pgoff_t(n) exact_type(pgoff_t, n)
+
+/**
+ * safe_conversion - perform a type conversion (cast) of an source value into
+ * a new variable, checking that the destination is large enough to hold the
+ * source value.
+ * @ptr: Destination pointer address
+ * @value: Source value
+ *
+ * Returns:
+ * If the value would overflow the destination, it returns false.
+ */
+#define safe_conversion(ptr, value) ({ \
+	typeof(value) __v = (value); \
+	typeof(ptr) __ptr = (ptr); \
+	overflows_type(__v, *__ptr) ? 0 : ((*__ptr = (typeof(*__ptr))__v), 1); \
+})
+
 /**
  * drm_can_sleep - returns true if currently okay to sleep
  *
-- 
2.34.1

[PATCH v5 2/7] drm/i915/gem: Typecheck page lookups

[Gwan-gyeong Mun]

From: Chris Wilson <chris@chris-wilson.co.uk>

We need to check that we avoid integer overflows when looking up a page,
and so fix all the instances where we have mistakenly used a plain
integer instead of a more suitable long. Be pedantic and add integer
typechecking to the lookup so that we can be sure that we are safe.
And it also uses pgoff_t as our page lookups must remain compatible with
the page cache, pgoff_t is currently exactly unsigned long.

v2: Move added i915_utils's macro into drm_util header (Jani N)
v3: Make not use the same macro name on a function. (Mauro)
    For kernel-doc, macros and functions are handled in the same namespace,
    the same macro name on a function prevents ever adding documentation
    for it.
v4: Add kernel-doc markups to the kAPI functions and macros (Mauoro)
v5: Fix an alignment to match open parenthesis

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.c    |   7 +-
 drivers/gpu/drm/i915/gem/i915_gem_object.h    | 293 ++++++++++++++++--
 drivers/gpu/drm/i915/gem/i915_gem_pages.c     |  27 +-
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c       |   2 +-
 .../drm/i915/gem/selftests/i915_gem_context.c |  12 +-
 .../drm/i915/gem/selftests/i915_gem_mman.c    |   8 +-
 .../drm/i915/gem/selftests/i915_gem_object.c  |   8 +-
 drivers/gpu/drm/i915/i915_gem.c               |  18 +-
 drivers/gpu/drm/i915/i915_vma.c               |   8 +-
 9 files changed, 322 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index ccec4055fde3..90996fe8ad45 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -421,10 +421,11 @@ void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
 static void
 i915_gem_object_read_from_page_kmap(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size)
 {
+	pgoff_t idx = offset >> PAGE_SHIFT;
 	void *src_map;
 	void *src_ptr;
 
-	src_map = kmap_atomic(i915_gem_object_get_page(obj, offset >> PAGE_SHIFT));
+	src_map = kmap_atomic(i915_gem_object_get_page(obj, idx));
 
 	src_ptr = src_map + offset_in_page(offset);
 	if (!(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ))
@@ -437,9 +438,10 @@ i915_gem_object_read_from_page_kmap(struct drm_i915_gem_object *obj, u64 offset,
 static void
 i915_gem_object_read_from_page_iomap(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size)
 {
+	pgoff_t idx = offset >> PAGE_SHIFT;
+	dma_addr_t dma = i915_gem_object_get_dma_address(obj, idx);
 	void __iomem *src_map;
 	void __iomem *src_ptr;
-	dma_addr_t dma = i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT);
 
 	src_map = io_mapping_map_wc(&obj->mm.region->iomap,
 				    dma - obj->mm.region->region.start,
@@ -468,6 +470,7 @@ i915_gem_object_read_from_page_iomap(struct drm_i915_gem_object *obj, u64 offset
  */
 int i915_gem_object_read_from_page(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size)
 {
+	GEM_BUG_ON(overflows_type(offset >> PAGE_SHIFT, pgoff_t));
 	GEM_BUG_ON(offset >= obj->base.size);
 	GEM_BUG_ON(offset_in_page(offset) > PAGE_SIZE - size);
 	GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 6f0a3ce35567..5da872afc4ba 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -27,8 +27,10 @@ enum intel_region_id;
  * spot such a local variable, please consider fixing!
  *
  * Aside from our own locals (for which we have no excuse!):
- * - sg_table embeds unsigned int for num_pages
- * - get_user_pages*() mixed ints with longs
+ * - sg_table embeds unsigned int for nents
+ *
+ * We can check for invalidly typed locals with typecheck(), see for example
+ * i915_gem_object_get_sg().
  */
 #define GEM_CHECK_SIZE_OVERFLOW(sz) \
 	GEM_WARN_ON((sz) >> PAGE_SHIFT > INT_MAX)
@@ -363,44 +365,289 @@ i915_gem_object_get_tile_row_size(const struct drm_i915_gem_object *obj)
 int i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
 			       unsigned int tiling, unsigned int stride);
 
+/**
+ * __i915_gem_object_page_iter_get_sg - helper to find the target scatterlist
+ * pointer and the target page position using pgoff_t n input argument and
+ * i915_gem_object_page_iter
+ * @obj: i915 GEM buffer object
+ * @iter: i915 GEM buffer object page iterator
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * Context: Takes and releases the mutex lock of the i915_gem_object_page_iter.
+ *          Takes and releases the RCU lock to search the radix_tree of
+ *          i915_gem_object_page_iter.
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * Recommended to use wrapper macro: i915_gem_object_page_iter_get_sg()
+ */
 struct scatterlist *
-__i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
-			 struct i915_gem_object_page_iter *iter,
-			 unsigned int n,
-			 unsigned int *offset, bool dma);
+__i915_gem_object_page_iter_get_sg(struct drm_i915_gem_object *obj,
+				   struct i915_gem_object_page_iter *iter,
+				   pgoff_t  n,
+				   unsigned int *offset);
 
+/**
+ * i915_gem_object_page_iter_get_sg - wrapper macro for
+ * __i915_gem_object_page_iter_get_sg()
+ * @obj: i915 GEM buffer object
+ * @it: i915 GEM buffer object page iterator
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * Context: Takes and releases the mutex lock of the i915_gem_object_page_iter.
+ *          Takes and releases the RCU lock to search the radix_tree of
+ *          i915_gem_object_page_iter.
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_page_iter_get_sg().
+ */
+#define i915_gem_object_page_iter_get_sg(obj, it, n, offset) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_page_iter_get_sg(obj, it, n, offset); \
+})
+
+/**
+ * __i915_gem_object_get_sg - helper to find the target scatterlist
+ * pointer and the target page position using pgoff_t n input argument and
+ * drm_i915_gem_object. It uses an internal shmem scatterlist lookup function.
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * It uses drm_i915_gem_object's internal shmem scatterlist lookup function as
+ * i915_gem_object_page_iter and calls __i915_gem_object_page_iter_get_sg().
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_sg()
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
 static inline struct scatterlist *
-i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
-		       unsigned int n,
-		       unsigned int *offset)
+__i915_gem_object_get_sg(struct drm_i915_gem_object *obj, pgoff_t n,
+			 unsigned int *offset)
 {
-	return __i915_gem_object_get_sg(obj, &obj->mm.get_page, n, offset, false);
+	return __i915_gem_object_page_iter_get_sg(obj, &obj->mm.get_page, n, offset);
 }
 
+/**
+ * i915_gem_object_get_sg - wrapper macro for __i915_gem_object_get_sg()
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_sg().
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
+#define i915_gem_object_get_sg(obj, n, offset) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_sg(obj, n, offset); \
+})
+
+/**
+ * __i915_gem_object_get_sg_dma - helper to find the target scatterlist
+ * pointer and the target page position using pgoff_t n input argument and
+ * drm_i915_gem_object. It uses an internal DMA mapped scatterlist lookup function
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * It uses drm_i915_gem_object's internal DMA mapped scatterlist lookup function
+ * as i915_gem_object_page_iter and calls __i915_gem_object_page_iter_get_sg().
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_sg_dma()
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
 static inline struct scatterlist *
-i915_gem_object_get_sg_dma(struct drm_i915_gem_object *obj,
-			   unsigned int n,
-			   unsigned int *offset)
+__i915_gem_object_get_sg_dma(struct drm_i915_gem_object *obj, pgoff_t n,
+			     unsigned int *offset)
 {
-	return __i915_gem_object_get_sg(obj, &obj->mm.get_dma_page, n, offset, true);
+	return __i915_gem_object_page_iter_get_sg(obj, &obj->mm.get_dma_page, n, offset);
 }
 
+/**
+ * i915_gem_object_get_sg_dma - wrapper macro for __i915_gem_object_get_sg_dma()
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @offset: searched physical offset,
+ *          it will be used for returning physical page offset value
+ *
+ * Returns:
+ * The target scatterlist pointer and the target page position.
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_sg_dma().
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
+#define i915_gem_object_get_sg_dma(obj, n, offset) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_sg_dma(obj, n, offset); \
+})
+
+/**
+ * __i915_gem_object_get_page - helper to find the target page with a page offset
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * It uses drm_i915_gem_object's internal shmem scatterlist lookup function as
+ * i915_gem_object_page_iter and calls __i915_gem_object_page_iter_get_sg()
+ * internally.
+ *
+ * Returns:
+ * The target page pointer.
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_page()
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
 struct page *
-i915_gem_object_get_page(struct drm_i915_gem_object *obj,
-			 unsigned int n);
+__i915_gem_object_get_page(struct drm_i915_gem_object *obj, pgoff_t n);
 
+/**
+ * i915_gem_object_get_page - wrapper macro for __i915_gem_object_get_page
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * Returns:
+ * The target page pointer.
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_page().
+ * See also __i915_gem_object_page_iter_get_sg()
+ */
+#define i915_gem_object_get_page(obj, n) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_page(obj, n); \
+})
+
+/**
+ * __i915_gem_object_get_dirty_page - helper to find the target page with a page
+ * offset
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * It works like i915_gem_object_get_page(), but it marks the returned page dirty.
+ *
+ * Returns:
+ * The target page pointer.
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_dirty_page()
+ * See also __i915_gem_object_page_iter_get_sg() and __i915_gem_object_get_page()
+ */
 struct page *
-i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
-			       unsigned int n);
+__i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, pgoff_t n);
+
+/**
+ * i915_gem_object_get_dirty_page - wrapper macro for __i915_gem_object_get_dirty_page
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * Returns:
+ * The target page pointer.
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_dirty_page().
+ * See also __i915_gem_object_page_iter_get_sg() and __i915_gem_object_get_page()
+ */
+#define i915_gem_object_get_dirty_page(obj, n) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_dirty_page(obj, n); \
+})
 
+/**
+ * __i915_gem_object_get_dma_address_len - helper to get bus addresses of
+ * targeted DMA mapped scatterlist from i915 GEM buffer object and it's length
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @len: DMA mapped scatterlist's DMA bus addresses length to return
+ *
+ * Returns:
+ * Bus addresses of targeted DMA mapped scatterlist
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_dma_address_len()
+ * See also __i915_gem_object_page_iter_get_sg() and __i915_gem_object_get_sg_dma()
+ */
 dma_addr_t
-i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
-				    unsigned long n,
-				    unsigned int *len);
+__i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, pgoff_t n,
+				      unsigned int *len);
 
+/**
+ * i915_gem_object_get_dma_address_len - wrapper macro for
+ * __i915_gem_object_get_dma_address_len
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ * @len: DMA mapped scatterlist's DMA bus addresses length to return
+ *
+ * Returns:
+ * Bus addresses of targeted DMA mapped scatterlist
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_dma_address_len().
+ * See also __i915_gem_object_page_iter_get_sg() and
+ * __i915_gem_object_get_dma_address_len()
+ */
+#define i915_gem_object_get_dma_address_len(obj, n, len) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_dma_address_len(obj, n, len); \
+})
+
+/**
+ * __i915_gem_object_get_dma_address - helper to get bus addresses of
+ * targeted DMA mapped scatterlist from i915 GEM buffer object
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * Returns:
+ * Bus addresses of targeted DMA mapped scatterlis
+ *
+ * Recommended to use wrapper macro: i915_gem_object_get_dma_address()
+ * See also __i915_gem_object_page_iter_get_sg() and __i915_gem_object_get_sg_dma()
+ */
 dma_addr_t
-i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
-				unsigned long n);
+__i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, pgoff_t n);
+
+/**
+ * i915_gem_object_get_dma_address - wrapper macro for
+ * __i915_gem_object_get_dma_address
+ * @obj: i915 GEM buffer object
+ * @n: page offset
+ *
+ * Returns:
+ * Bus addresses of targeted DMA mapped scatterlist
+ *
+ * In order to avoid the truncation of the input parameter, it checks the page
+ * offset n's type from the input parameter before calling
+ * __i915_gem_object_get_dma_address().
+ * See also __i915_gem_object_page_iter_get_sg() and
+ * __i915_gem_object_get_dma_address()
+ */
+#define i915_gem_object_get_dma_address(obj, n) ({ \
+	exactly_pgoff_t(n); \
+	__i915_gem_object_get_dma_address(obj, n); \
+})
 
 void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 				 struct sg_table *pages,
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 97c820eee115..f994573cdcb1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -503,14 +503,16 @@ void __i915_gem_object_release_map(struct drm_i915_gem_object *obj)
 }
 
 struct scatterlist *
-__i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
-			 struct i915_gem_object_page_iter *iter,
-			 unsigned int n,
-			 unsigned int *offset,
-			 bool dma)
+__i915_gem_object_page_iter_get_sg(struct drm_i915_gem_object *obj,
+				   struct i915_gem_object_page_iter *iter,
+				   pgoff_t n,
+				   unsigned int *offset)
+
 {
-	struct scatterlist *sg;
+	const bool dma = iter == &obj->mm.get_dma_page ||
+			 iter == &obj->ttm.get_io_page;
 	unsigned int idx, count;
+	struct scatterlist *sg;
 
 	might_sleep();
 	GEM_BUG_ON(n >= obj->base.size >> PAGE_SHIFT);
@@ -618,7 +620,7 @@ __i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 }
 
 struct page *
-i915_gem_object_get_page(struct drm_i915_gem_object *obj, unsigned int n)
+__i915_gem_object_get_page(struct drm_i915_gem_object *obj, pgoff_t n)
 {
 	struct scatterlist *sg;
 	unsigned int offset;
@@ -631,8 +633,7 @@ i915_gem_object_get_page(struct drm_i915_gem_object *obj, unsigned int n)
 
 /* Like i915_gem_object_get_page(), but mark the returned page dirty */
 struct page *
-i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
-			       unsigned int n)
+__i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, pgoff_t n)
 {
 	struct page *page;
 
@@ -644,9 +645,8 @@ i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
 }
 
 dma_addr_t
-i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
-				    unsigned long n,
-				    unsigned int *len)
+__i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
+				      pgoff_t n, unsigned int *len)
 {
 	struct scatterlist *sg;
 	unsigned int offset;
@@ -660,8 +660,7 @@ i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
 }
 
 dma_addr_t
-i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
-				unsigned long n)
+__i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, pgoff_t n)
 {
 	return i915_gem_object_get_dma_address_len(obj, n, NULL);
 }
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 5a5cf332d8a5..52c4c1fac7f9 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -724,7 +724,7 @@ static unsigned long i915_ttm_io_mem_pfn(struct ttm_buffer_object *bo,
 	GEM_WARN_ON(bo->ttm);
 
 	base = obj->mm.region->iomap.base - obj->mm.region->region.start;
-	sg = __i915_gem_object_get_sg(obj, &obj->ttm.get_io_page, page_offset, &ofs, true);
+	sg = i915_gem_object_page_iter_get_sg(obj, &obj->ttm.get_io_page, page_offset, &ofs);
 
 	return ((base + sg_dma_address(sg)) >> PAGE_SHIFT) + ofs;
 }
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
index c6ad67b90e8a..a18a890e681f 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
@@ -455,7 +455,8 @@ static int gpu_fill(struct intel_context *ce,
 static int cpu_fill(struct drm_i915_gem_object *obj, u32 value)
 {
 	const bool has_llc = HAS_LLC(to_i915(obj->base.dev));
-	unsigned int n, m, need_flush;
+	unsigned int need_flush;
+	unsigned long n, m;
 	int err;
 
 	i915_gem_object_lock(obj, NULL);
@@ -485,7 +486,8 @@ static int cpu_fill(struct drm_i915_gem_object *obj, u32 value)
 static noinline int cpu_check(struct drm_i915_gem_object *obj,
 			      unsigned int idx, unsigned int max)
 {
-	unsigned int n, m, needs_flush;
+	unsigned int needs_flush;
+	unsigned long n;
 	int err;
 
 	i915_gem_object_lock(obj, NULL);
@@ -494,7 +496,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj,
 		goto out_unlock;
 
 	for (n = 0; n < real_page_count(obj); n++) {
-		u32 *map;
+		u32 *map, m;
 
 		map = kmap_atomic(i915_gem_object_get_page(obj, n));
 		if (needs_flush & CLFLUSH_BEFORE)
@@ -502,7 +504,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj,
 
 		for (m = 0; m < max; m++) {
 			if (map[m] != m) {
-				pr_err("%pS: Invalid value at object %d page %d/%ld, offset %d/%d: found %x expected %x\n",
+				pr_err("%pS: Invalid value at object %d page %ld/%ld, offset %d/%d: found %x expected %x\n",
 				       __builtin_return_address(0), idx,
 				       n, real_page_count(obj), m, max,
 				       map[m], m);
@@ -513,7 +515,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj,
 
 		for (; m < DW_PER_PAGE; m++) {
 			if (map[m] != STACK_MAGIC) {
-				pr_err("%pS: Invalid value at object %d page %d, offset %d: found %x expected %x (uninitialised)\n",
+				pr_err("%pS: Invalid value at object %d page %ld, offset %d: found %x expected %x (uninitialised)\n",
 				       __builtin_return_address(0), idx, n, m,
 				       map[m], STACK_MAGIC);
 				err = -EINVAL;
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index 3ced9948a331..86e435d42546 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -95,11 +95,11 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_ggtt_view view;
 	struct i915_vma *vma;
+	unsigned long offset;
 	unsigned long page;
 	u32 __iomem *io;
 	struct page *p;
 	unsigned int n;
-	u64 offset;
 	u32 *cpu;
 	int err;
 
@@ -156,7 +156,7 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 	cpu = kmap(p) + offset_in_page(offset);
 	drm_clflush_virt_range(cpu, sizeof(*cpu));
 	if (*cpu != (u32)page) {
-		pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n",
+		pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%lu + %u [0x%lx]) of 0x%x, found 0x%x\n",
 		       page, n,
 		       view.partial.offset,
 		       view.partial.size,
@@ -212,10 +212,10 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
 	for_each_prime_number_from(page, 1, npages) {
 		struct i915_ggtt_view view =
 			compute_partial_view(obj, page, MIN_CHUNK_PAGES);
+		unsigned long offset;
 		u32 __iomem *io;
 		struct page *p;
 		unsigned int n;
-		u64 offset;
 		u32 *cpu;
 
 		GEM_BUG_ON(view.partial.size > nreal);
@@ -252,7 +252,7 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
 		cpu = kmap(p) + offset_in_page(offset);
 		drm_clflush_virt_range(cpu, sizeof(*cpu));
 		if (*cpu != (u32)page) {
-			pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n",
+			pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%lu + %u [0x%lx]) of 0x%x, found 0x%x\n",
 			       page, n,
 			       view.partial.offset,
 			       view.partial.size,
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c
index fe0a890775e2..bf30763ee6bc 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c
@@ -33,10 +33,10 @@ static int igt_gem_object(void *arg)
 
 static int igt_gem_huge(void *arg)
 {
-	const unsigned int nreal = 509; /* just to be awkward */
+	const unsigned long nreal = 509; /* just to be awkward */
 	struct drm_i915_private *i915 = arg;
 	struct drm_i915_gem_object *obj;
-	unsigned int n;
+	unsigned long n;
 	int err;
 
 	/* Basic sanitycheck of our huge fake object allocation */
@@ -49,7 +49,7 @@ static int igt_gem_huge(void *arg)
 
 	err = i915_gem_object_pin_pages_unlocked(obj);
 	if (err) {
-		pr_err("Failed to allocate %u pages (%lu total), err=%d\n",
+		pr_err("Failed to allocate %lu pages (%lu total), err=%d\n",
 		       nreal, obj->base.size / PAGE_SIZE, err);
 		goto out;
 	}
@@ -57,7 +57,7 @@ static int igt_gem_huge(void *arg)
 	for (n = 0; n < obj->base.size / PAGE_SIZE; n++) {
 		if (i915_gem_object_get_page(obj, n) !=
 		    i915_gem_object_get_page(obj, n % nreal)) {
-			pr_err("Page lookup mismatch at index %u [%u]\n",
+			pr_err("Page lookup mismatch at index %lu [%lu]\n",
 			       n, n % nreal);
 			err = -EINVAL;
 			goto out_unpin;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 702e5b89be22..dba58a3c3238 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -229,8 +229,9 @@ i915_gem_shmem_pread(struct drm_i915_gem_object *obj,
 		     struct drm_i915_gem_pread *args)
 {
 	unsigned int needs_clflush;
-	unsigned int idx, offset;
 	char __user *user_data;
+	unsigned long offset;
+	pgoff_t idx;
 	u64 remain;
 	int ret;
 
@@ -383,13 +384,17 @@ i915_gem_gtt_pread(struct drm_i915_gem_object *obj,
 {
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_ggtt *ggtt = to_gt(i915)->ggtt;
+	unsigned long remain, offset;
 	intel_wakeref_t wakeref;
 	struct drm_mm_node node;
 	void __user *user_data;
 	struct i915_vma *vma;
-	u64 remain, offset;
 	int ret = 0;
 
+	if (overflows_type(args->size, remain) ||
+	    overflows_type(args->offset, offset))
+		return -EINVAL;
+
 	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
 
 	vma = i915_gem_gtt_prepare(obj, &node, false);
@@ -540,13 +545,17 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_ggtt *ggtt = to_gt(i915)->ggtt;
 	struct intel_runtime_pm *rpm = &i915->runtime_pm;
+	unsigned long remain, offset;
 	intel_wakeref_t wakeref;
 	struct drm_mm_node node;
 	struct i915_vma *vma;
-	u64 remain, offset;
 	void __user *user_data;
 	int ret = 0;
 
+	if (overflows_type(args->size, remain) ||
+	    overflows_type(args->offset, offset))
+		return -EINVAL;
+
 	if (i915_gem_object_has_struct_page(obj)) {
 		/*
 		 * Avoid waking the device up if we can fallback, as
@@ -654,8 +663,9 @@ i915_gem_shmem_pwrite(struct drm_i915_gem_object *obj,
 {
 	unsigned int partial_cacheline_write;
 	unsigned int needs_clflush;
-	unsigned int offset, idx;
 	void __user *user_data;
+	unsigned long offset;
+	pgoff_t idx;
 	u64 remain;
 	int ret;
 
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index ef3b04c7e153..28443c77b45a 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -911,7 +911,7 @@ rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset,
 	     struct sg_table *st, struct scatterlist *sg)
 {
 	unsigned int column, row;
-	unsigned int src_idx;
+	pgoff_t src_idx;
 
 	for (column = 0; column < width; column++) {
 		unsigned int left;
@@ -1017,7 +1017,7 @@ add_padding_pages(unsigned int count,
 
 static struct scatterlist *
 remap_tiled_color_plane_pages(struct drm_i915_gem_object *obj,
-			      unsigned int offset, unsigned int alignment_pad,
+			      unsigned long offset, unsigned int alignment_pad,
 			      unsigned int width, unsigned int height,
 			      unsigned int src_stride, unsigned int dst_stride,
 			      struct sg_table *st, struct scatterlist *sg,
@@ -1076,7 +1076,7 @@ remap_tiled_color_plane_pages(struct drm_i915_gem_object *obj,
 
 static struct scatterlist *
 remap_contiguous_pages(struct drm_i915_gem_object *obj,
-		       unsigned int obj_offset,
+		       pgoff_t obj_offset,
 		       unsigned int count,
 		       struct sg_table *st, struct scatterlist *sg)
 {
@@ -1109,7 +1109,7 @@ remap_contiguous_pages(struct drm_i915_gem_object *obj,
 
 static struct scatterlist *
 remap_linear_color_plane_pages(struct drm_i915_gem_object *obj,
-			       unsigned int obj_offset, unsigned int alignment_pad,
+			       pgoff_t obj_offset, unsigned int alignment_pad,
 			       unsigned int size,
 			       struct sg_table *st, struct scatterlist *sg,
 			       unsigned int *gtt_offset)
-- 
2.34.1

[PATCH v5 3/7] drm/i915: Check for integer truncation on scatterlist creation

[Gwan-gyeong Mun]

From: Chris Wilson <chris@chris-wilson.co.uk>

There is an impedance mismatch between the scatterlist API using unsigned
int and our memory/page accounting in unsigned long. That is we may try
to create a scatterlist for a large object that overflows returning a
small table into which we try to fit very many pages. As the object size
is under control of userspace, we have to be prudent and catch the
conversion errors.

To catch the implicit truncation as we switch from unsigned long into the
scatterlist's unsigned int, we use overflows_type check and report
E2BIG prior to the operation. This is already used in our create ioctls to
indicate if the uABI request is simply too large for the backing store.
Failing that type check, we have a second check at sg_alloc_table time
to make sure the values we are passing into the scatterlist API are not
truncated.

It uses pgoff_t for locals that are dealing with page indices, in this
case, the page count is the limit of the page index.
And it uses safe_conversion() macro which performs a type conversion (cast)
of an integer value into a new variable, checking that the destination is
large enough to hold the source value.

v2: Move added i915_utils's macro into drm_util header (Jani N)
v5: Fix macros to be enclosed in parentheses for complex values
    Fix too long line warning

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Brian Welty <brian.welty@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_internal.c |  6 ++++--
 drivers/gpu/drm/i915/gem/i915_gem_object.h   |  3 ---
 drivers/gpu/drm/i915/gem/i915_gem_phys.c     |  4 ++++
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c    |  5 ++++-
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c      |  4 ++++
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c  |  5 ++++-
 drivers/gpu/drm/i915/gvt/dmabuf.c            |  9 +++++----
 drivers/gpu/drm/i915/i915_scatterlist.h      | 11 +++++++++++
 8 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
index c698f95af15f..ff2e6e780631 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
@@ -37,10 +37,13 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
 	struct sg_table *st;
 	struct scatterlist *sg;
 	unsigned int sg_page_sizes;
-	unsigned int npages;
+	pgoff_t npages; /* restricted by sg_alloc_table */
 	int max_order;
 	gfp_t gfp;
 
+	if (!safe_conversion(&npages, obj->base.size >> PAGE_SHIFT))
+		return -E2BIG;
+
 	max_order = MAX_ORDER;
 #ifdef CONFIG_SWIOTLB
 	if (is_swiotlb_active(obj->base.dev->dev)) {
@@ -67,7 +70,6 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
 	if (!st)
 		return -ENOMEM;
 
-	npages = obj->base.size / PAGE_SIZE;
 	if (sg_alloc_table(st, npages, GFP_KERNEL)) {
 		kfree(st);
 		return -ENOMEM;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 5da872afc4ba..0cf31adbfd41 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -26,9 +26,6 @@ enum intel_region_id;
  * this and catch if we ever need to fix it. In the meantime, if you do
  * spot such a local variable, please consider fixing!
  *
- * Aside from our own locals (for which we have no excuse!):
- * - sg_table embeds unsigned int for nents
- *
  * We can check for invalidly typed locals with typecheck(), see for example
  * i915_gem_object_get_sg().
  */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_phys.c b/drivers/gpu/drm/i915/gem/i915_gem_phys.c
index 0d0e46dae559..88ba7266a3a5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_phys.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_phys.c
@@ -28,6 +28,10 @@ static int i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
 	void *dst;
 	int i;
 
+	/* Contiguous chunk, with a single scatterlist element */
+	if (overflows_type(obj->base.size, sg->length))
+		return -E2BIG;
+
 	if (GEM_WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
 		return -EINVAL;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 4eed3dd90ba8..604e8829e8ea 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -193,13 +193,16 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj)
 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct intel_memory_region *mem = obj->mm.region;
 	struct address_space *mapping = obj->base.filp->f_mapping;
-	const unsigned long page_count = obj->base.size / PAGE_SIZE;
 	unsigned int max_segment = i915_sg_segment_size();
 	struct sg_table *st;
 	struct sgt_iter sgt_iter;
+	pgoff_t page_count;
 	struct page *page;
 	int ret;
 
+	if (!safe_conversion(&page_count, obj->base.size >> PAGE_SHIFT))
+		return -E2BIG;
+
 	/*
 	 * Assert that the object is not currently in any GPU domain. As it
 	 * wasn't in the GTT, there shouldn't be any way it could have been in
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 52c4c1fac7f9..9f2be1892b6c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -822,6 +822,10 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
 {
 	struct ttm_place requested, busy[I915_TTM_MAX_PLACEMENTS];
 	struct ttm_placement placement;
+	pgoff_t num_pages;
+
+	if (!safe_conversion(&num_pages, obj->base.size >> PAGE_SHIFT))
+		return -E2BIG;
 
 	GEM_BUG_ON(obj->mm.n_placements > I915_TTM_MAX_PLACEMENTS);
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index 094f06b4ce33..25785c3a0083 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -128,13 +128,16 @@ static void i915_gem_object_userptr_drop_ref(struct drm_i915_gem_object *obj)
 
 static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
 {
-	const unsigned long num_pages = obj->base.size >> PAGE_SHIFT;
 	unsigned int max_segment = i915_sg_segment_size();
 	struct sg_table *st;
 	unsigned int sg_page_sizes;
 	struct page **pvec;
+	pgoff_t num_pages; /* limited by sg_alloc_table_from_pages_segment */
 	int ret;
 
+	if (!safe_conversion(&num_pages, obj->base.size >> PAGE_SHIFT))
+		return -E2BIG;
+
 	st = kmalloc(sizeof(*st), GFP_KERNEL);
 	if (!st)
 		return -ENOMEM;
diff --git a/drivers/gpu/drm/i915/gvt/dmabuf.c b/drivers/gpu/drm/i915/gvt/dmabuf.c
index 01e54b45c5c1..795270cb4ec2 100644
--- a/drivers/gpu/drm/i915/gvt/dmabuf.c
+++ b/drivers/gpu/drm/i915/gvt/dmabuf.c
@@ -42,8 +42,7 @@
 
 #define GEN8_DECODE_PTE(pte) (pte & GENMASK_ULL(63, 12))
 
-static int vgpu_gem_get_pages(
-		struct drm_i915_gem_object *obj)
+static int vgpu_gem_get_pages(struct drm_i915_gem_object *obj)
 {
 	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
 	struct intel_vgpu *vgpu;
@@ -52,7 +51,10 @@ static int vgpu_gem_get_pages(
 	int i, j, ret;
 	gen8_pte_t __iomem *gtt_entries;
 	struct intel_vgpu_fb_info *fb_info;
-	u32 page_num;
+	pgoff_t page_num;
+
+	if (!safe_conversion(&page_num, obj->base.size >> PAGE_SHIFT))
+		return -E2BIG;
 
 	fb_info = (struct intel_vgpu_fb_info *)obj->gvt_info;
 	if (drm_WARN_ON(&dev_priv->drm, !fb_info))
@@ -66,7 +68,6 @@ static int vgpu_gem_get_pages(
 	if (unlikely(!st))
 		return -ENOMEM;
 
-	page_num = obj->base.size >> PAGE_SHIFT;
 	ret = sg_alloc_table(st, page_num, GFP_KERNEL);
 	if (ret) {
 		kfree(st);
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h b/drivers/gpu/drm/i915/i915_scatterlist.h
index 9ddb3e743a3e..1d1802beb42b 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.h
+++ b/drivers/gpu/drm/i915/i915_scatterlist.h
@@ -220,4 +220,15 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
 						     u64 region_start,
 						     u32 page_alignment);
 
+/* Wrap scatterlist.h to sanity check for integer truncation */
+typedef unsigned int __sg_size_t; /* see linux/scatterlist.h */
+#define sg_alloc_table(sgt, nents, gfp) \
+	overflows_type(nents, __sg_size_t) ? -E2BIG \
+		: ((sg_alloc_table)(sgt, (__sg_size_t)(nents), gfp))
+
+#define sg_alloc_table_from_pages_segment(sgt, pages, npages, offset, size, max_segment, gfp) \
+	overflows_type(npages, __sg_size_t) ? -E2BIG \
+		: ((sg_alloc_table_from_pages_segment)(sgt, pages, (__sg_size_t)(npages), offset, \
+						       size, max_segment, gfp))
+
 #endif
-- 
2.34.1

[PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

[Gwan-gyeong Mun]

There is an impedance mismatch between the first/last valid page
frame number of ttm place in unsigned and our memory/page accounting in
unsigned long.
As the object size is under the control of userspace, we have to be prudent
and catch the conversion errors.
To catch the implicit truncation as we switch from unsigned long to
unsigned, we use overflows_type check and report E2BIG or overflow_type
prior to the operation.

v3: Not to change execution inside a macro. (Mauro)
    Add safe_conversion_gem_bug_on() macro and remove temporal
    SAFE_CONVERSION() macro.

v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c |  6 +++---
 drivers/gpu/drm/i915/i915_gem.h         |  4 ++++
 drivers/gpu/drm/i915/intel_region_ttm.c | 20 +++++++++++++++++---
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 9f2be1892b6c..88f2887627dc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -140,14 +140,14 @@ i915_ttm_place_from_region(const struct intel_memory_region *mr,
 	if (flags & I915_BO_ALLOC_CONTIGUOUS)
 		place->flags |= TTM_PL_FLAG_CONTIGUOUS;
 	if (offset != I915_BO_INVALID_OFFSET) {
-		place->fpfn = offset >> PAGE_SHIFT;
-		place->lpfn = place->fpfn + (size >> PAGE_SHIFT);
+		safe_conversion_gem_bug_on(&place->fpfn, offset >> PAGE_SHIFT);
+		safe_conversion_gem_bug_on(&place->lpfn, place->fpfn + (size >> PAGE_SHIFT));
 	} else if (mr->io_size && mr->io_size < mr->total) {
 		if (flags & I915_BO_ALLOC_GPU_ONLY) {
 			place->flags |= TTM_PL_FLAG_TOPDOWN;
 		} else {
 			place->fpfn = 0;
-			place->lpfn = mr->io_size >> PAGE_SHIFT;
+			safe_conversion_gem_bug_on(&place->lpfn, mr->io_size >> PAGE_SHIFT);
 		}
 	}
 }
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 68d8d52bd541..327dacedd5d1 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -83,5 +83,9 @@ struct drm_i915_private;
 #endif
 
 #define I915_GEM_IDLE_TIMEOUT (HZ / 5)
+#define safe_conversion_gem_bug_on(ptr, value) !({ \
+	safe_conversion(ptr, value) ? 0 \
+		: (({ GEM_BUG_ON(overflows_type(value, *ptr)); }), 1); \
+})
 
 #endif /* __I915_GEM_H__ */
diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
index 575d67bc6ffe..f0d143948725 100644
--- a/drivers/gpu/drm/i915/intel_region_ttm.c
+++ b/drivers/gpu/drm/i915/intel_region_ttm.c
@@ -209,14 +209,26 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
 	if (flags & I915_BO_ALLOC_CONTIGUOUS)
 		place.flags |= TTM_PL_FLAG_CONTIGUOUS;
 	if (offset != I915_BO_INVALID_OFFSET) {
-		place.fpfn = offset >> PAGE_SHIFT;
-		place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
+		if (!safe_conversion_gem_bug_on(&place.fpfn,
+						offset >> PAGE_SHIFT)) {
+			ret = -E2BIG;
+			goto out;
+		}
+		if (!safe_conversion_gem_bug_on(&place.lpfn,
+						place.fpfn + (size >> PAGE_SHIFT))) {
+			ret = -E2BIG;
+			goto out;
+		}
 	} else if (mem->io_size && mem->io_size < mem->total) {
 		if (flags & I915_BO_ALLOC_GPU_ONLY) {
 			place.flags |= TTM_PL_FLAG_TOPDOWN;
 		} else {
 			place.fpfn = 0;
-			place.lpfn = mem->io_size >> PAGE_SHIFT;
+			if (!safe_conversion_gem_bug_on(&place.lpfn,
+							mem->io_size >> PAGE_SHIFT)) {
+				ret = -E2BIG;
+				goto out;
+			}
 		}
 	}
 
@@ -224,6 +236,8 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
 	mock_bo.bdev = &mem->i915->bdev;
 
 	ret = man->func->alloc(man, &mock_bo, &place, &res);
+
+out:
 	if (ret == -ENOSPC)
 		ret = -ENXIO;
 	if (!ret)
-- 
2.34.1

[PATCH v5 5/7] drm/i915: Check if the size is too big while creating shmem file

[Gwan-gyeong Mun]

The __shmem_file_setup() function returns -EINVAL if size is greater than
MAX_LFS_FILESIZE. To handle the same error as other code that returns
-E2BIG when the size is too large, it add a code that returns -E2BIG when
the size is larger than the size that can be handled.

v4: If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false, so it
    checks only when BITS_PER_LONG is 64.

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 604e8829e8ea..d41569ca6999 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -541,6 +541,20 @@ static int __create_shmem(struct drm_i915_private *i915,
 
 	drm_gem_private_object_init(&i915->drm, obj, size);
 
+	/* XXX: The __shmem_file_setup() function returns -EINVAL if size is
+	 * greater than MAX_LFS_FILESIZE.
+	 * To handle the same error as other code that returns -E2BIG when
+	 * the size is too large, we add a code that returns -E2BIG when the
+	 * size is larger than the size that can be handled.
+	 * If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false,
+	 * so we only needs to check when BITS_PER_LONG is 64.
+	 * If BITS_PER_LONG is 32, E2BIG checks are processed when
+	 * i915_gem_object_size_2big() is called before init_object() callback
+	 * is called.
+	 */
+	if (BITS_PER_LONG == 64 && size > MAX_LFS_FILESIZE)
+		return -E2BIG;
+
 	if (i915->mm.gemfs)
 		filp = shmem_file_setup_with_mnt(i915->mm.gemfs, "i915", size,
 						 flags);
-- 
2.34.1

[PATCH v5 6/7] drm/i915: Use error code as -E2BIG when the size of gem ttm object is too large

[Gwan-gyeong Mun]

The ttm_bo_init_reserved() functions returns -ENOSPC if the size is too big
to add vma. The direct function that returns -ENOSPC is drm_mm_insert_node_in_range().
To handle the same error as other code returning -E2BIG when the size is
too large, it converts return value to -E2BIG.

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 88f2887627dc..4d478bf325be 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -1249,6 +1249,17 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,
 	ret = ttm_bo_init_reserved(&i915->bdev, i915_gem_to_ttm(obj), bo_type,
 				   &i915_sys_placement, page_size >> PAGE_SHIFT,
 				   &ctx, NULL, NULL, i915_ttm_bo_destroy);
+
+	/*
+	 * XXX: The ttm_bo_init_reserved() functions returns -ENOSPC if the size
+	 * is too big to add vma. The direct function that returns -ENOSPC is
+	 * drm_mm_insert_node_in_range(). To handle the same error as other code
+	 * that returns -E2BIG when the size is too large, it converts -ENOSPC to
+	 * -E2BIG.
+	 */
+	if (size >> PAGE_SHIFT > INT_MAX && ret == -ENOSPC)
+		ret = -E2BIG;
+
 	if (ret)
 		return i915_ttm_err_to_gem(ret);
 
-- 
2.34.1

[PATCH v5 7/7] drm/i915: Remove truncation warning for large objects

[Gwan-gyeong Mun]

From: Chris Wilson <chris@chris-wilson.co.uk>

Having addressed the issues surrounding incorrect types for local
variables and potential integer truncation in using the scatterlist API,
we have closed all the loop holes we had previously identified with
dangerously large object creation. As such, we can eliminate the warning
put in place to remind us to complete the review.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Brian Welty <brian.welty@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Testcase: igt@gem_create@create-massive
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4991
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.h | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 0cf31adbfd41..dd2762da332f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -20,25 +20,10 @@
 
 enum intel_region_id;
 
-/*
- * XXX: There is a prevalence of the assumption that we fit the
- * object's page count inside a 32bit _signed_ variable. Let's document
- * this and catch if we ever need to fix it. In the meantime, if you do
- * spot such a local variable, please consider fixing!
- *
- * We can check for invalidly typed locals with typecheck(), see for example
- * i915_gem_object_get_sg().
- */
-#define GEM_CHECK_SIZE_OVERFLOW(sz) \
-	GEM_WARN_ON((sz) >> PAGE_SHIFT > INT_MAX)
-
 static inline bool i915_gem_object_size_2big(u64 size)
 {
 	struct drm_i915_gem_object *obj;
 
-	if (GEM_CHECK_SIZE_OVERFLOW(size))
-		return true;
-
 	if (overflows_type(size, obj->base.size))
 		return true;
 
-- 
2.34.1

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> It moves overflows_type utility macro into drm util header from i915_utils
> header. The overflows_type can be used to catch the truncation between data
> types. And it adds safe_conversion() macro which performs a type conversion
> (cast) of an source value into a new variable, checking that the
> destination is large enough to hold the source value.
> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
> while compiling.
> 
> v3: Add is_type_unsigned() macro (Mauro)
>      Modify overflows_type() macro to consider signed data types (Mauro)
>      Fix the problem that safe_conversion() macro always returns true
> v4: Fix kernel-doc markups
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Nirmoy Das <nirmoy.das@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
>   drivers/gpu/drm/i915/i915_utils.h |  5 +-
>   include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
>   2 files changed, 78 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
> index c10d68cdc3ca..345e5b2dc1cd 100644
> --- a/drivers/gpu/drm/i915/i915_utils.h
> +++ b/drivers/gpu/drm/i915/i915_utils.h
> @@ -32,6 +32,7 @@
>   #include <linux/types.h>
>   #include <linux/workqueue.h>
>   #include <linux/sched/clock.h>
> +#include <drm/drm_util.h>
>   
>   #ifdef CONFIG_X86
>   #include <asm/hypervisor.h>
> @@ -111,10 +112,6 @@ bool i915_error_injected(void);
>   #define range_overflows_end_t(type, start, size, max) \
>   	range_overflows_end((type)(start), (type)(size), (type)(max))
>   
> -/* Note we don't consider signbits :| */
> -#define overflows_type(x, T) \
> -	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))
> -
>   #define ptr_mask_bits(ptr, n) ({					\
>   	unsigned long __v = (unsigned long)(ptr);			\
>   	(typeof(ptr))(__v & -BIT(n));					\
> diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h
> index 79952d8c4bba..1de9ee5704fa 100644
> --- a/include/drm/drm_util.h
> +++ b/include/drm/drm_util.h
> @@ -62,6 +62,83 @@
>    */
>   #define for_each_if(condition) if (!(condition)) {} else
>   
> +/**
> + * is_type_unsigned - helper for checking data type which is an unsigned data
> + * type or not
> + * @x: The data type to check
> + *
> + * Returns:
> + * True if the data type is an unsigned data type, false otherwise.
> + */
> +#define is_type_unsigned(x) ((typeof(x))-1 >= (typeof(x))0)
> +
> +/**
> + * overflows_type - helper for checking the truncation between data types
> + * @x: Source for overflow type comparison
> + * @T: Destination for overflow type comparison
> + *
> + * It compares the values and size of each data type between the first and
> + * second argument to check whether truncation can occur when assigning the
> + * first argument to the variable of the second argument.
> + * Source and Destination can be used with or without sign bit.
> + * Composite data structures such as union and structure are not considered.
> + * Enum data types are not considered.
> + * Floating point data types are not considered.
> + *
> + * Returns:
> + * True if truncation can occur, false otherwise.
> + */
> +
> +#define overflows_type(x, T) \
> +	(is_type_unsigned(x) ? \
> +		is_type_unsigned(T) ? \
> +			(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +			: (sizeof(x) >= sizeof(T) && (x) >> (BITS_PER_TYPE(T) - 1)) ? 1 : 0 \
> +	: is_type_unsigned(T) ? \
> +		((x) < 0) ? 1 : (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +		: (sizeof(x) > sizeof(T)) ? \
> +			((x) < 0) ? (((x) * -1) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +				: ((x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +			: 0)


It became quite big and hard to read. I wonder if we could not just 
check the effects of the conversion, sth like:
#define overflows_type(x, T) ((T)(x) != (x))

Regards
Andrzej


> +
> +/**
> + * exact_type - break compile if source type and destination value's type are
> + * not the same
> + * @T: Source type
> + * @n: Destination value
> + *
> + * It is a helper macro for a poor man's -Wconversion: only allow variables of
> + * an exact type. It determines whether the source type and destination value's
> + * type are the same while compiling, and it breaks compile if two types are
> + * not the same
> + */
> +#define exact_type(T, n) \
> +	BUILD_BUG_ON(!__builtin_constant_p(n) && !__builtin_types_compatible_p(T, typeof(n)))
> +
> +/**
> + * exactly_pgoff_t - helper to check if the type of a value is pgoff_t
> + * @n: value to compare pgoff_t type
> + *
> + * It breaks compile if the argument value's type is not pgoff_t type.
> + */
> +#define exactly_pgoff_t(n) exact_type(pgoff_t, n)
> +
> +/**
> + * safe_conversion - perform a type conversion (cast) of an source value into
> + * a new variable, checking that the destination is large enough to hold the
> + * source value.
> + * @ptr: Destination pointer address
> + * @value: Source value
> + *
> + * Returns:
> + * If the value would overflow the destination, it returns false.
> + */
> +#define safe_conversion(ptr, value) ({ \
> +	typeof(value) __v = (value); \
> +	typeof(ptr) __ptr = (ptr); \
> +	overflows_type(__v, *__ptr) ? 0 : ((*__ptr = (typeof(*__ptr))__v), 1); \
> +})
> +
>   /**
>    * drm_can_sleep - returns true if currently okay to sleep
>    *

Re: [Intel-gfx] [PATCH v5 2/7] drm/i915/gem: Typecheck page lookups

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> We need to check that we avoid integer overflows when looking up a page,
> and so fix all the instances where we have mistakenly used a plain
> integer instead of a more suitable long. Be pedantic and add integer
> typechecking to the lookup so that we can be sure that we are safe.
> And it also uses pgoff_t as our page lookups must remain compatible with
> the page cache, pgoff_t is currently exactly unsigned long.
> 
> v2: Move added i915_utils's macro into drm_util header (Jani N)
> v3: Make not use the same macro name on a function. (Mauro)
>      For kernel-doc, macros and functions are handled in the same namespace,
>      the same macro name on a function prevents ever adding documentation
>      for it.
> v4: Add kernel-doc markups to the kAPI functions and macros (Mauoro)
> v5: Fix an alignment to match open parenthesis
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej

Re: [Intel-gfx] [PATCH v5 3/7] drm/i915: Check for integer truncation on scatterlist creation

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> There is an impedance mismatch between the scatterlist API using unsigned
> int and our memory/page accounting in unsigned long. That is we may try
> to create a scatterlist for a large object that overflows returning a
> small table into which we try to fit very many pages. As the object size
> is under control of userspace, we have to be prudent and catch the
> conversion errors.
> 
> To catch the implicit truncation as we switch from unsigned long into the
> scatterlist's unsigned int, we use overflows_type check and report
> E2BIG prior to the operation. This is already used in our create ioctls to
> indicate if the uABI request is simply too large for the backing store.
> Failing that type check, we have a second check at sg_alloc_table time
> to make sure the values we are passing into the scatterlist API are not
> truncated.
> 
> It uses pgoff_t for locals that are dealing with page indices, in this
> case, the page count is the limit of the page index.
> And it uses safe_conversion() macro which performs a type conversion (cast)
> of an integer value into a new variable, checking that the destination is
> large enough to hold the source value.
> 
> v2: Move added i915_utils's macro into drm_util header (Jani N)
> v5: Fix macros to be enclosed in parentheses for complex values
>      Fix too long line warning
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Brian Welty <brian.welty@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej

Re: [Intel-gfx] [PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> There is an impedance mismatch between the first/last valid page
> frame number of ttm place in unsigned and our memory/page accounting in
> unsigned long.
> As the object size is under the control of userspace, we have to be prudent
> and catch the conversion errors.
> To catch the implicit truncation as we switch from unsigned long to
> unsigned, we use overflows_type check and report E2BIG or overflow_type
> prior to the operation.
> 
> v3: Not to change execution inside a macro. (Mauro)
>      Add safe_conversion_gem_bug_on() macro and remove temporal
>      SAFE_CONVERSION() macro.
> 
> v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>

Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej

Re: [Intel-gfx] [PATCH v5 5/7] drm/i915: Check if the size is too big while creating shmem file

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> The __shmem_file_setup() function returns -EINVAL if size is greater than
> MAX_LFS_FILESIZE. To handle the same error as other code that returns
> -E2BIG when the size is too large, it add a code that returns -E2BIG when
> the size is larger than the size that can be handled.
> 
> v4: If BITS_PER_LONG is 32, size > MAX_LFS_FILESIZE is always false, so it
>      checks only when BITS_PER_LONG is 64.
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>

Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej

Re: [Intel-gfx] [PATCH v5 6/7] drm/i915: Use error code as -E2BIG when the size of gem ttm object is too large

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> The ttm_bo_init_reserved() functions returns -ENOSPC if the size is too big
> to add vma. The direct function that returns -ENOSPC is drm_mm_insert_node_in_range().
> To handle the same error as other code returning -E2BIG when the size is
> too large, it converts return value to -E2BIG.
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 88f2887627dc..4d478bf325be 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -1249,6 +1249,17 @@ int __i915_gem_ttm_object_init(struct intel_memory_region *mem,
>   	ret = ttm_bo_init_reserved(&i915->bdev, i915_gem_to_ttm(obj), bo_type,
>   				   &i915_sys_placement, page_size >> PAGE_SHIFT,
>   				   &ctx, NULL, NULL, i915_ttm_bo_destroy);
> +
> +	/*
> +	 * XXX: The ttm_bo_init_reserved() functions returns -ENOSPC if the size
> +	 * is too big to add vma. The direct function that returns -ENOSPC is
> +	 * drm_mm_insert_node_in_range(). To handle the same error as other code
> +	 * that returns -E2BIG when the size is too large, it converts -ENOSPC to
> +	 * -E2BIG.
> +	 */
> +	if (size >> PAGE_SHIFT > INT_MAX && ret == -ENOSPC)
> +		ret = -E2BIG;
> +
>   	if (ret)
>   		return i915_ttm_err_to_gem(ret);
>   

Re: [Intel-gfx] [PATCH v5 7/7] drm/i915: Remove truncation warning for large objects

[Andrzej Hajda]

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Having addressed the issues surrounding incorrect types for local
> variables and potential integer truncation in using the scatterlist API,
> we have closed all the loop holes we had previously identified with
> dangerously large object creation. As such, we can eliminate the warning
> put in place to remind us to complete the review.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Brian Welty <brian.welty@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Testcase: igt@gem_create@create-massive
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4991
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>

Regards
Andrzej

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Gwan-gyeong Mun]

On 7/25/22 2:36 PM, Andrzej Hajda wrote:
> On 25.07.2022 11:25, Gwan-gyeong Mun wrote:
>> It moves overflows_type utility macro into drm util header from 
>> i915_utils
>> header. The overflows_type can be used to catch the truncation between 
>> data
>> types. And it adds safe_conversion() macro which performs a type 
>> conversion
>> (cast) of an source value into a new variable, checking that the
>> destination is large enough to hold the source value.
>> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
>> while compiling.
>>
>> v3: Add is_type_unsigned() macro (Mauro)
>>      Modify overflows_type() macro to consider signed data types (Mauro)
>>      Fix the problem that safe_conversion() macro always returns true
>> v4: Fix kernel-doc markups
>>
>> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: Nirmoy Das <nirmoy.das@intel.com>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
>> ---
>>   drivers/gpu/drm/i915/i915_utils.h |  5 +-
>>   include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
>>   2 files changed, 78 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_utils.h 
>> b/drivers/gpu/drm/i915/i915_utils.h
>> index c10d68cdc3ca..345e5b2dc1cd 100644
>> --- a/drivers/gpu/drm/i915/i915_utils.h
>> +++ b/drivers/gpu/drm/i915/i915_utils.h
>> @@ -32,6 +32,7 @@
>>   #include <linux/types.h>
>>   #include <linux/workqueue.h>
>>   #include <linux/sched/clock.h>
>> +#include <drm/drm_util.h>
>>   #ifdef CONFIG_X86
>>   #include <asm/hypervisor.h>
>> @@ -111,10 +112,6 @@ bool i915_error_injected(void);
>>   #define range_overflows_end_t(type, start, size, max) \
>>       range_overflows_end((type)(start), (type)(size), (type)(max))
>> -/* Note we don't consider signbits :| */
>> -#define overflows_type(x, T) \
>> -    (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))
>> -
>>   #define ptr_mask_bits(ptr, n) ({                    \
>>       unsigned long __v = (unsigned long)(ptr);            \
>>       (typeof(ptr))(__v & -BIT(n));                    \
>> diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h
>> index 79952d8c4bba..1de9ee5704fa 100644
>> --- a/include/drm/drm_util.h
>> +++ b/include/drm/drm_util.h
>> @@ -62,6 +62,83 @@
>>    */
>>   #define for_each_if(condition) if (!(condition)) {} else
>> +/**
>> + * is_type_unsigned - helper for checking data type which is an 
>> unsigned data
>> + * type or not
>> + * @x: The data type to check
>> + *
>> + * Returns:
>> + * True if the data type is an unsigned data type, false otherwise.
>> + */
>> +#define is_type_unsigned(x) ((typeof(x))-1 >= (typeof(x))0)
>> +
>> +/**
>> + * overflows_type - helper for checking the truncation between data 
>> types
>> + * @x: Source for overflow type comparison
>> + * @T: Destination for overflow type comparison
>> + *
>> + * It compares the values and size of each data type between the 
>> first and
>> + * second argument to check whether truncation can occur when 
>> assigning the
>> + * first argument to the variable of the second argument.
>> + * Source and Destination can be used with or without sign bit.
>> + * Composite data structures such as union and structure are not 
>> considered.
>> + * Enum data types are not considered.
>> + * Floating point data types are not considered.
>> + *
>> + * Returns:
>> + * True if truncation can occur, false otherwise.
>> + */
>> +
>> +#define overflows_type(x, T) \
>> +    (is_type_unsigned(x) ? \
>> +        is_type_unsigned(T) ? \
>> +            (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +            : (sizeof(x) >= sizeof(T) && (x) >> (BITS_PER_TYPE(T) - 
>> 1)) ? 1 : 0 \
>> +    : is_type_unsigned(T) ? \
>> +        ((x) < 0) ? 1 : (sizeof(x) > sizeof(T) && (x) >> 
>> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +        : (sizeof(x) > sizeof(T)) ? \
>> +            ((x) < 0) ? (((x) * -1) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +                : ((x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +            : 0)
> 
> 
> It became quite big and hard to read. I wonder if we could not just 
> check the effects of the conversion, sth like:
> #define overflows_type(x, T) ((T)(x) != (x))
> 
Yes, this macro is a bit difficult to read because it takes into account 
multiple situations. I left a comment with the relevant details in reply 
to the previous patch so that you could check the details of the macro.

And the macro you commented is not satisfactory in all use cases where 
the overflows_type() macro is used.
If you refer to the bottom part of the link below, you can check the 
pseudo code of this macro and test scenarios of the use cases covered by 
this macro. (It also includes the test code.)
https://patchwork.freedesktop.org/patch/492374/?series=104704&rev=3

Br,
G.G.

> Regards
> Andrzej
> 
> 
>> +
>> +/**
>> + * exact_type - break compile if source type and destination value's 
>> type are
>> + * not the same
>> + * @T: Source type
>> + * @n: Destination value
>> + *
>> + * It is a helper macro for a poor man's -Wconversion: only allow 
>> variables of
>> + * an exact type. It determines whether the source type and 
>> destination value's
>> + * type are the same while compiling, and it breaks compile if two 
>> types are
>> + * not the same
>> + */
>> +#define exact_type(T, n) \
>> +    BUILD_BUG_ON(!__builtin_constant_p(n) && 
>> !__builtin_types_compatible_p(T, typeof(n)))
>> +
>> +/**
>> + * exactly_pgoff_t - helper to check if the type of a value is pgoff_t
>> + * @n: value to compare pgoff_t type
>> + *
>> + * It breaks compile if the argument value's type is not pgoff_t type.
>> + */
>> +#define exactly_pgoff_t(n) exact_type(pgoff_t, n)
>> +
>> +/**
>> + * safe_conversion - perform a type conversion (cast) of an source 
>> value into
>> + * a new variable, checking that the destination is large enough to 
>> hold the
>> + * source value.
>> + * @ptr: Destination pointer address
>> + * @value: Source value
>> + *
>> + * Returns:
>> + * If the value would overflow the destination, it returns false.
>> + */
>> +#define safe_conversion(ptr, value) ({ \
>> +    typeof(value) __v = (value); \
>> +    typeof(ptr) __ptr = (ptr); \
>> +    overflows_type(__v, *__ptr) ? 0 : ((*__ptr = 
>> (typeof(*__ptr))__v), 1); \
>> +})
>> +
>>   /**
>>    * drm_can_sleep - returns true if currently okay to sleep
>>    *
> 

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Andi Shyti]

Hi,

On Mon, Jul 25, 2022 at 12:25:22PM +0300, Gwan-gyeong Mun wrote:
> It moves overflows_type utility macro into drm util header from i915_utils
> header. The overflows_type can be used to catch the truncation between data
> types. And it adds safe_conversion() macro which performs a type conversion
> (cast) of an source value into a new variable, checking that the
> destination is large enough to hold the source value.
> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
> while compiling.
> 
> v3: Add is_type_unsigned() macro (Mauro)
>     Modify overflows_type() macro to consider signed data types (Mauro)
>     Fix the problem that safe_conversion() macro always returns true
> v4: Fix kernel-doc markups
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Nirmoy Das <nirmoy.das@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
>  drivers/gpu/drm/i915/i915_utils.h |  5 +-
>  include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
>  2 files changed, 78 insertions(+), 4 deletions(-)

Jani and Mauro suggested to have this macro in
include/drm/drm_util.h.

Can I please have an ack from one of the drm maintainers so that
I can go ahead an apply this series?

Thanks,
Andi

> 
> diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
> index c10d68cdc3ca..345e5b2dc1cd 100644
> --- a/drivers/gpu/drm/i915/i915_utils.h
> +++ b/drivers/gpu/drm/i915/i915_utils.h
> @@ -32,6 +32,7 @@
>  #include <linux/types.h>
>  #include <linux/workqueue.h>
>  #include <linux/sched/clock.h>
> +#include <drm/drm_util.h>
>  
>  #ifdef CONFIG_X86
>  #include <asm/hypervisor.h>
> @@ -111,10 +112,6 @@ bool i915_error_injected(void);
>  #define range_overflows_end_t(type, start, size, max) \
>  	range_overflows_end((type)(start), (type)(size), (type)(max))
>  
> -/* Note we don't consider signbits :| */
> -#define overflows_type(x, T) \
> -	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))
> -
>  #define ptr_mask_bits(ptr, n) ({					\
>  	unsigned long __v = (unsigned long)(ptr);			\
>  	(typeof(ptr))(__v & -BIT(n));					\
> diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h
> index 79952d8c4bba..1de9ee5704fa 100644
> --- a/include/drm/drm_util.h
> +++ b/include/drm/drm_util.h
> @@ -62,6 +62,83 @@
>   */
>  #define for_each_if(condition) if (!(condition)) {} else
>  
> +/**
> + * is_type_unsigned - helper for checking data type which is an unsigned data
> + * type or not
> + * @x: The data type to check
> + *
> + * Returns:
> + * True if the data type is an unsigned data type, false otherwise.
> + */
> +#define is_type_unsigned(x) ((typeof(x))-1 >= (typeof(x))0)
> +
> +/**
> + * overflows_type - helper for checking the truncation between data types
> + * @x: Source for overflow type comparison
> + * @T: Destination for overflow type comparison
> + *
> + * It compares the values and size of each data type between the first and
> + * second argument to check whether truncation can occur when assigning the
> + * first argument to the variable of the second argument.
> + * Source and Destination can be used with or without sign bit.
> + * Composite data structures such as union and structure are not considered.
> + * Enum data types are not considered.
> + * Floating point data types are not considered.
> + *
> + * Returns:
> + * True if truncation can occur, false otherwise.
> + */
> +
> +#define overflows_type(x, T) \
> +	(is_type_unsigned(x) ? \
> +		is_type_unsigned(T) ? \
> +			(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +			: (sizeof(x) >= sizeof(T) && (x) >> (BITS_PER_TYPE(T) - 1)) ? 1 : 0 \
> +	: is_type_unsigned(T) ? \
> +		((x) < 0) ? 1 : (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +		: (sizeof(x) > sizeof(T)) ? \
> +			((x) < 0) ? (((x) * -1) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +				: ((x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
> +			: 0)
> +
> +/**
> + * exact_type - break compile if source type and destination value's type are
> + * not the same
> + * @T: Source type
> + * @n: Destination value
> + *
> + * It is a helper macro for a poor man's -Wconversion: only allow variables of
> + * an exact type. It determines whether the source type and destination value's
> + * type are the same while compiling, and it breaks compile if two types are
> + * not the same
> + */
> +#define exact_type(T, n) \
> +	BUILD_BUG_ON(!__builtin_constant_p(n) && !__builtin_types_compatible_p(T, typeof(n)))
> +
> +/**
> + * exactly_pgoff_t - helper to check if the type of a value is pgoff_t
> + * @n: value to compare pgoff_t type
> + *
> + * It breaks compile if the argument value's type is not pgoff_t type.
> + */
> +#define exactly_pgoff_t(n) exact_type(pgoff_t, n)
> +
> +/**
> + * safe_conversion - perform a type conversion (cast) of an source value into
> + * a new variable, checking that the destination is large enough to hold the
> + * source value.
> + * @ptr: Destination pointer address
> + * @value: Source value
> + *
> + * Returns:
> + * If the value would overflow the destination, it returns false.
> + */
> +#define safe_conversion(ptr, value) ({ \
> +	typeof(value) __v = (value); \
> +	typeof(ptr) __ptr = (ptr); \
> +	overflows_type(__v, *__ptr) ? 0 : ((*__ptr = (typeof(*__ptr))__v), 1); \
> +})
> +
>  /**
>   * drm_can_sleep - returns true if currently okay to sleep
>   *
> -- 
> 2.34.1

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Jani Nikula]

On Wed, 27 Jul 2022, Andi Shyti <andi.shyti@linux.intel.com> wrote:
> Hi,
>
> On Mon, Jul 25, 2022 at 12:25:22PM +0300, Gwan-gyeong Mun wrote:
>> It moves overflows_type utility macro into drm util header from i915_utils
>> header. The overflows_type can be used to catch the truncation between data
>> types. And it adds safe_conversion() macro which performs a type conversion
>> (cast) of an source value into a new variable, checking that the
>> destination is large enough to hold the source value.
>> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
>> while compiling.
>> 
>> v3: Add is_type_unsigned() macro (Mauro)
>>     Modify overflows_type() macro to consider signed data types (Mauro)
>>     Fix the problem that safe_conversion() macro always returns true
>> v4: Fix kernel-doc markups
>> 
>> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: Nirmoy Das <nirmoy.das@intel.com>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
>> ---
>>  drivers/gpu/drm/i915/i915_utils.h |  5 +-
>>  include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
>>  2 files changed, 78 insertions(+), 4 deletions(-)
>
> Jani and Mauro suggested to have this macro in
> include/drm/drm_util.h.

I can't recall suggesting such a thing. The macros in question have
nothing specifically to do with i915 *or* drm. They are generic, and
should be in generic kernel headers.

We must stop piling up generic and generally useful stuff in our own
headers.

I thought I've been clear about this all along.


BR,
Jani.




>
> Can I please have an ack from one of the drm maintainers so that
> I can go ahead an apply this series?
>
> Thanks,
> Andi
>
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
>> index c10d68cdc3ca..345e5b2dc1cd 100644
>> --- a/drivers/gpu/drm/i915/i915_utils.h
>> +++ b/drivers/gpu/drm/i915/i915_utils.h
>> @@ -32,6 +32,7 @@
>>  #include <linux/types.h>
>>  #include <linux/workqueue.h>
>>  #include <linux/sched/clock.h>
>> +#include <drm/drm_util.h>
>>  
>>  #ifdef CONFIG_X86
>>  #include <asm/hypervisor.h>
>> @@ -111,10 +112,6 @@ bool i915_error_injected(void);
>>  #define range_overflows_end_t(type, start, size, max) \
>>  	range_overflows_end((type)(start), (type)(size), (type)(max))
>>  
>> -/* Note we don't consider signbits :| */
>> -#define overflows_type(x, T) \
>> -	(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T))
>> -
>>  #define ptr_mask_bits(ptr, n) ({					\
>>  	unsigned long __v = (unsigned long)(ptr);			\
>>  	(typeof(ptr))(__v & -BIT(n));					\
>> diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h
>> index 79952d8c4bba..1de9ee5704fa 100644
>> --- a/include/drm/drm_util.h
>> +++ b/include/drm/drm_util.h
>> @@ -62,6 +62,83 @@
>>   */
>>  #define for_each_if(condition) if (!(condition)) {} else
>>  
>> +/**
>> + * is_type_unsigned - helper for checking data type which is an unsigned data
>> + * type or not
>> + * @x: The data type to check
>> + *
>> + * Returns:
>> + * True if the data type is an unsigned data type, false otherwise.
>> + */
>> +#define is_type_unsigned(x) ((typeof(x))-1 >= (typeof(x))0)
>> +
>> +/**
>> + * overflows_type - helper for checking the truncation between data types
>> + * @x: Source for overflow type comparison
>> + * @T: Destination for overflow type comparison
>> + *
>> + * It compares the values and size of each data type between the first and
>> + * second argument to check whether truncation can occur when assigning the
>> + * first argument to the variable of the second argument.
>> + * Source and Destination can be used with or without sign bit.
>> + * Composite data structures such as union and structure are not considered.
>> + * Enum data types are not considered.
>> + * Floating point data types are not considered.
>> + *
>> + * Returns:
>> + * True if truncation can occur, false otherwise.
>> + */
>> +
>> +#define overflows_type(x, T) \
>> +	(is_type_unsigned(x) ? \
>> +		is_type_unsigned(T) ? \
>> +			(sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +			: (sizeof(x) >= sizeof(T) && (x) >> (BITS_PER_TYPE(T) - 1)) ? 1 : 0 \
>> +	: is_type_unsigned(T) ? \
>> +		((x) < 0) ? 1 : (sizeof(x) > sizeof(T) && (x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +		: (sizeof(x) > sizeof(T)) ? \
>> +			((x) < 0) ? (((x) * -1) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +				: ((x) >> BITS_PER_TYPE(T)) ? 1 : 0 \
>> +			: 0)
>> +
>> +/**
>> + * exact_type - break compile if source type and destination value's type are
>> + * not the same
>> + * @T: Source type
>> + * @n: Destination value
>> + *
>> + * It is a helper macro for a poor man's -Wconversion: only allow variables of
>> + * an exact type. It determines whether the source type and destination value's
>> + * type are the same while compiling, and it breaks compile if two types are
>> + * not the same
>> + */
>> +#define exact_type(T, n) \
>> +	BUILD_BUG_ON(!__builtin_constant_p(n) && !__builtin_types_compatible_p(T, typeof(n)))
>> +
>> +/**
>> + * exactly_pgoff_t - helper to check if the type of a value is pgoff_t
>> + * @n: value to compare pgoff_t type
>> + *
>> + * It breaks compile if the argument value's type is not pgoff_t type.
>> + */
>> +#define exactly_pgoff_t(n) exact_type(pgoff_t, n)
>> +
>> +/**
>> + * safe_conversion - perform a type conversion (cast) of an source value into
>> + * a new variable, checking that the destination is large enough to hold the
>> + * source value.
>> + * @ptr: Destination pointer address
>> + * @value: Source value
>> + *
>> + * Returns:
>> + * If the value would overflow the destination, it returns false.
>> + */
>> +#define safe_conversion(ptr, value) ({ \
>> +	typeof(value) __v = (value); \
>> +	typeof(ptr) __ptr = (ptr); \
>> +	overflows_type(__v, *__ptr) ? 0 : ((*__ptr = (typeof(*__ptr))__v), 1); \
>> +})
>> +
>>  /**
>>   * drm_can_sleep - returns true if currently okay to sleep
>>   *
>> -- 
>> 2.34.1

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

[Jani Nikula]

On Mon, 25 Jul 2022, Gwan-gyeong Mun <gwan-gyeong.mun@intel.com> wrote:
> There is an impedance mismatch between the first/last valid page
> frame number of ttm place in unsigned and our memory/page accounting in
> unsigned long.
> As the object size is under the control of userspace, we have to be prudent
> and catch the conversion errors.
> To catch the implicit truncation as we switch from unsigned long to
> unsigned, we use overflows_type check and report E2BIG or overflow_type
> prior to the operation.
>
> v3: Not to change execution inside a macro. (Mauro)
>     Add safe_conversion_gem_bug_on() macro and remove temporal
>     SAFE_CONVERSION() macro.
>
> v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()
>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c |  6 +++---
>  drivers/gpu/drm/i915/i915_gem.h         |  4 ++++
>  drivers/gpu/drm/i915/intel_region_ttm.c | 20 +++++++++++++++++---
>  3 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 9f2be1892b6c..88f2887627dc 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -140,14 +140,14 @@ i915_ttm_place_from_region(const struct intel_memory_region *mr,
>  	if (flags & I915_BO_ALLOC_CONTIGUOUS)
>  		place->flags |= TTM_PL_FLAG_CONTIGUOUS;
>  	if (offset != I915_BO_INVALID_OFFSET) {
> -		place->fpfn = offset >> PAGE_SHIFT;
> -		place->lpfn = place->fpfn + (size >> PAGE_SHIFT);
> +		safe_conversion_gem_bug_on(&place->fpfn, offset >> PAGE_SHIFT);
> +		safe_conversion_gem_bug_on(&place->lpfn, place->fpfn + (size >> PAGE_SHIFT));

So the natural thing would be to have and use two orthogonal helpers, a
safe_conversion predicate and a warn:

	GEM_BUG_ON(!safe_conversion(...));

or even:

	if (GEM_BUG_ON(!safe_conversion(...)))
		/* ... */

But GEM_BUG_ON() is surprising and does not follow the same pattern as
WARN_ON/BUG_ON. *sigh*

BR,
Jani.


>  	} else if (mr->io_size && mr->io_size < mr->total) {
>  		if (flags & I915_BO_ALLOC_GPU_ONLY) {
>  			place->flags |= TTM_PL_FLAG_TOPDOWN;
>  		} else {
>  			place->fpfn = 0;
> -			place->lpfn = mr->io_size >> PAGE_SHIFT;
> +			safe_conversion_gem_bug_on(&place->lpfn, mr->io_size >> PAGE_SHIFT);
>  		}
>  	}
>  }
> diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
> index 68d8d52bd541..327dacedd5d1 100644
> --- a/drivers/gpu/drm/i915/i915_gem.h
> +++ b/drivers/gpu/drm/i915/i915_gem.h
> @@ -83,5 +83,9 @@ struct drm_i915_private;
>  #endif
>  
>  #define I915_GEM_IDLE_TIMEOUT (HZ / 5)
> +#define safe_conversion_gem_bug_on(ptr, value) !({ \
> +	safe_conversion(ptr, value) ? 0 \
> +		: (({ GEM_BUG_ON(overflows_type(value, *ptr)); }), 1); \
> +})
>  
>  #endif /* __I915_GEM_H__ */
> diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c b/drivers/gpu/drm/i915/intel_region_ttm.c
> index 575d67bc6ffe..f0d143948725 100644
> --- a/drivers/gpu/drm/i915/intel_region_ttm.c
> +++ b/drivers/gpu/drm/i915/intel_region_ttm.c
> @@ -209,14 +209,26 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
>  	if (flags & I915_BO_ALLOC_CONTIGUOUS)
>  		place.flags |= TTM_PL_FLAG_CONTIGUOUS;
>  	if (offset != I915_BO_INVALID_OFFSET) {
> -		place.fpfn = offset >> PAGE_SHIFT;
> -		place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
> +		if (!safe_conversion_gem_bug_on(&place.fpfn,
> +						offset >> PAGE_SHIFT)) {
> +			ret = -E2BIG;
> +			goto out;
> +		}
> +		if (!safe_conversion_gem_bug_on(&place.lpfn,
> +						place.fpfn + (size >> PAGE_SHIFT))) {
> +			ret = -E2BIG;
> +			goto out;
> +		}
>  	} else if (mem->io_size && mem->io_size < mem->total) {
>  		if (flags & I915_BO_ALLOC_GPU_ONLY) {
>  			place.flags |= TTM_PL_FLAG_TOPDOWN;
>  		} else {
>  			place.fpfn = 0;
> -			place.lpfn = mem->io_size >> PAGE_SHIFT;
> +			if (!safe_conversion_gem_bug_on(&place.lpfn,
> +							mem->io_size >> PAGE_SHIFT)) {
> +				ret = -E2BIG;
> +				goto out;
> +			}
>  		}
>  	}
>  
> @@ -224,6 +236,8 @@ intel_region_ttm_resource_alloc(struct intel_memory_region *mem,
>  	mock_bo.bdev = &mem->i915->bdev;
>  
>  	ret = man->func->alloc(man, &mock_bo, &place, &res);
> +
> +out:
>  	if (ret == -ENOSPC)
>  		ret = -ENXIO;
>  	if (!ret)

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Andi Shyti]

Hi Jani,

> >> It moves overflows_type utility macro into drm util header from i915_utils
> >> header. The overflows_type can be used to catch the truncation between data
> >> types. And it adds safe_conversion() macro which performs a type conversion
> >> (cast) of an source value into a new variable, checking that the
> >> destination is large enough to hold the source value.
> >> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
> >> while compiling.
> >> 
> >> v3: Add is_type_unsigned() macro (Mauro)
> >>     Modify overflows_type() macro to consider signed data types (Mauro)
> >>     Fix the problem that safe_conversion() macro always returns true
> >> v4: Fix kernel-doc markups
> >> 
> >> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> >> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> >> Cc: Matthew Auld <matthew.auld@intel.com>
> >> Cc: Nirmoy Das <nirmoy.das@intel.com>
> >> Cc: Jani Nikula <jani.nikula@intel.com>
> >> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> >> ---
> >>  drivers/gpu/drm/i915/i915_utils.h |  5 +-
> >>  include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
> >>  2 files changed, 78 insertions(+), 4 deletions(-)
> >
> > Jani and Mauro suggested to have this macro in
> > include/drm/drm_util.h.
> 
> I can't recall suggesting such a thing. The macros in question have
> nothing specifically to do with i915 *or* drm. They are generic, and
> should be in generic kernel headers.
> 
> We must stop piling up generic and generally useful stuff in our own
> headers.

Yes, I agree with you and I think there was already such
discussion whether to move this into generic kernel headers or in
drm header.

Gwan-gyeong, any thoughts or further plans to move this to a
different place? It's been already three people (and I'm
including myself here) recommending to have this in a different
place.

Andi

> I thought I've been clear about this all along.

Thanks, Jani!

Andi

Re: [Intel-gfx] [PATCH v5 1/7] drm: Move and add a few utility macros into drm util header

[Gwan-gyeong Mun]

On 8/4/22 12:06 PM, Andi Shyti wrote:
> Hi Jani,
> 
>>>> It moves overflows_type utility macro into drm util header from i915_utils
>>>> header. The overflows_type can be used to catch the truncation between data
>>>> types. And it adds safe_conversion() macro which performs a type conversion
>>>> (cast) of an source value into a new variable, checking that the
>>>> destination is large enough to hold the source value.
>>>> And it adds exact_type and exactly_pgoff_t macro to catch type mis-match
>>>> while compiling.
>>>>
>>>> v3: Add is_type_unsigned() macro (Mauro)
>>>>      Modify overflows_type() macro to consider signed data types (Mauro)
>>>>      Fix the problem that safe_conversion() macro always returns true
>>>> v4: Fix kernel-doc markups
>>>>
>>>> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
>>>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>>>> Cc: Matthew Auld <matthew.auld@intel.com>
>>>> Cc: Nirmoy Das <nirmoy.das@intel.com>
>>>> Cc: Jani Nikula <jani.nikula@intel.com>
>>>> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
>>>> ---
>>>>   drivers/gpu/drm/i915/i915_utils.h |  5 +-
>>>>   include/drm/drm_util.h            | 77 +++++++++++++++++++++++++++++++
>>>>   2 files changed, 78 insertions(+), 4 deletions(-)
>>>
>>> Jani and Mauro suggested to have this macro in
>>> include/drm/drm_util.h.
>>
>> I can't recall suggesting such a thing. The macros in question have
>> nothing specifically to do with i915 *or* drm. They are generic, and
>> should be in generic kernel headers.
>>
>> We must stop piling up generic and generally useful stuff in our own
>> headers.
> 
> Yes, I agree with you and I think there was already such
> discussion whether to move this into generic kernel headers or in
> drm header.
> 
> Gwan-gyeong, any thoughts or further plans to move this to a
> different place? It's been already three people (and I'm
> including myself here) recommending to have this in a different
> place.
> 
> Andi
> 

Yes, except for the i915, there was no use case in the code, so I moved 
the header file here, but thanks to many people's comments, I will move 
these utility macros to a more generic place and send a new patch.

Thank you for checking again and for your comments.

Many thanks, Andi, Jani, Mauro.

G.G.

>> I thought I've been clear about this all along.
> 
> Thanks, Jani!
> 
> Andi
>