[PATCH v3 4/8] slab: Add __alloc_size attributes for better bounds checking

[Kees Cook <keescook@chromium.org>]

As already done in GrapheneOS, add the __alloc_size attribute for regular
kmalloc interfaces, to provide additional hinting for better bounds
checking, assisting CONFIG_FORTIFY_SOURCE and other compiler
optimizations.

Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Co-developed-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
---
 include/linux/slab.h | 61 ++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index d9f14125d7a2..844b776deecf 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -181,7 +181,7 @@ int kmem_cache_shrink(struct kmem_cache *s);
 /*
  * Common kmalloc functions provided by all allocators
  */
-void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags);
+void * __must_check krealloc(const void *objp, size_t new_size, gfp_t flags) __alloc_size(2);
 void kfree(const void *objp);
 void kfree_sensitive(const void *objp);
 size_t __ksize(const void *objp);
@@ -425,7 +425,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
 #define kmalloc_index(s) __kmalloc_index(s, true)
 #endif /* !CONFIG_SLOB */
 
-void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc;
+void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
 void *kmem_cache_alloc(struct kmem_cache *s, gfp_t flags) __assume_slab_alignment __malloc;
 void kmem_cache_free(struct kmem_cache *s, void *objp);
 
@@ -449,11 +449,12 @@ static __always_inline void kfree_bulk(size_t size, void **p)
 }
 
 #ifdef CONFIG_NUMA
-void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment __malloc;
+void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment
+							 __alloc_size(1);
 void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment
 									 __malloc;
 #else
-static __always_inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
+static __always_inline __alloc_size(1) void *__kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	return __kmalloc(size, flags);
 }
@@ -466,23 +467,23 @@ static __always_inline void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t f
 
 #ifdef CONFIG_TRACING
 extern void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
-				   __assume_slab_alignment __malloc;
+				   __assume_slab_alignment __alloc_size(3);
 
 #ifdef CONFIG_NUMA
 extern void *kmem_cache_alloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
-					 int node, size_t size) __assume_slab_alignment __malloc;
+					 int node, size_t size) __assume_slab_alignment
+								__alloc_size(4);
 #else
-static __always_inline void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
-							 gfp_t gfpflags, int node,
-							 size_t size)
+static __always_inline __alloc_size(4) void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
+						 gfp_t gfpflags, int node, size_t size)
 {
 	return kmem_cache_alloc_trace(s, gfpflags, size);
 }
 #endif /* CONFIG_NUMA */
 
 #else /* CONFIG_TRACING */
-static __always_inline void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t flags,
-						    size_t size)
+static __always_inline __alloc_size(3) void *kmem_cache_alloc_trace(struct kmem_cache *s,
+								    gfp_t flags, size_t size)
 {
 	void *ret = kmem_cache_alloc(s, flags);
 
@@ -501,19 +502,20 @@ static __always_inline void *kmem_cache_alloc_node_trace(struct kmem_cache *s, g
 #endif /* CONFIG_TRACING */
 
 extern void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) __assume_page_alignment
-									 __malloc;
+									 __alloc_size(1);
 
 #ifdef CONFIG_TRACING
 extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
-				__assume_page_alignment __malloc;
+				__assume_page_alignment __alloc_size(1);
 #else
-static __always_inline void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
+static __always_inline __alloc_size(1) void *kmalloc_order_trace(size_t size, gfp_t flags,
+								 unsigned int order)
 {
 	return kmalloc_order(size, flags, order);
 }
 #endif
 
-static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
+static __always_inline __alloc_size(1) void *kmalloc_large(size_t size, gfp_t flags)
 {
 	unsigned int order = get_order(size);
 	return kmalloc_order_trace(size, flags, order);
@@ -573,7 +575,7 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
  *	Try really hard to succeed the allocation but fail
  *	eventually.
  */
-static __always_inline void *kmalloc(size_t size, gfp_t flags)
+static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 {
 	if (__builtin_constant_p(size)) {
 #ifndef CONFIG_SLOB
@@ -595,7 +597,7 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
 	return __kmalloc(size, flags);
 }
 
-static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
+static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 #ifndef CONFIG_SLOB
 	if (__builtin_constant_p(size) &&
@@ -619,7 +621,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
  * @size: element size.
  * @flags: the type of memory to allocate (see kmalloc).
  */
-static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
+static inline __alloc_size(1, 2) void *kmalloc_array(size_t n, size_t size, gfp_t flags)
 {
 	size_t bytes;
 
@@ -637,8 +639,10 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
  * @new_size: new size of a single member of the array
  * @flags: the type of memory to allocate (see kmalloc)
  */
-static inline void * __must_check krealloc_array(void *p, size_t new_n, size_t new_size,
-						 gfp_t flags)
+static inline __alloc_size(2, 3) void * __must_check krealloc_array(void *p,
+								    size_t new_n,
+								    size_t new_size,
+								    gfp_t flags)
 {
 	size_t bytes;
 
@@ -654,7 +658,7 @@ static inline void * __must_check krealloc_array(void *p, size_t new_n, size_t n
  * @size: element size.
  * @flags: the type of memory to allocate (see kmalloc).
  */
-static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+static inline __alloc_size(1, 2) void *kcalloc(size_t n, size_t size, gfp_t flags)
 {
 	return kmalloc_array(n, size, flags | __GFP_ZERO);
 }
@@ -667,12 +671,13 @@ static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
  * allocator where we care about the real place the memory allocation
  * request comes from.
  */
-extern void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller);
+extern void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
+				   __alloc_size(1);
 #define kmalloc_track_caller(size, flags) \
 	__kmalloc_track_caller(size, flags, _RET_IP_)
 
-static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
-				       int node)
+static inline __alloc_size(1, 2) void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
+							  int node)
 {
 	size_t bytes;
 
@@ -683,7 +688,7 @@ static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
 	return __kmalloc_node(bytes, flags, node);
 }
 
-static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
+static inline __alloc_size(1, 2) void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
 {
 	return kmalloc_array_node(n, size, flags | __GFP_ZERO, node);
 }
@@ -691,7 +696,7 @@ static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
 
 #ifdef CONFIG_NUMA
 extern void *__kmalloc_node_track_caller(size_t size, gfp_t flags, int node,
-					 unsigned long caller);
+					 unsigned long caller) __alloc_size(1);
 #define kmalloc_node_track_caller(size, flags, node) \
 	__kmalloc_node_track_caller(size, flags, node, \
 			_RET_IP_)
@@ -716,7 +721,7 @@ static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kmalloc).
  */
-static inline void *kzalloc(size_t size, gfp_t flags)
+static inline __alloc_size(1) void *kzalloc(size_t size, gfp_t flags)
 {
 	return kmalloc(size, flags | __GFP_ZERO);
 }
@@ -727,7 +732,7 @@ static inline void *kzalloc(size_t size, gfp_t flags)
  * @flags: the type of memory to allocate (see kmalloc).
  * @node: memory node from which to allocate
  */
-static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
+static inline __alloc_size(1) void *kzalloc_node(size_t size, gfp_t flags, int node)
 {
 	return kmalloc_node(size, flags | __GFP_ZERO, node);
 }
-- 
2.30.2