From: Alexander Potapenko <glider@google.com>
To: glider@google.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@google.com>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>, Christoph Hellwig <hch@lst.de>,
Christoph Lameter <cl@linux.com>,
David Rientjes <rientjes@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Eric Dumazet <edumazet@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Ilya Leoshkevich <iii@linux.ibm.com>,
Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kees Cook <keescook@chromium.org>, Marco Elver <elver@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Matthew Wilcox <willy@infradead.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Pekka Enberg <penberg@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vasily Gorbik <gor@linux.ibm.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 14/48] kmsan: implement kmsan_init(), initialize READ_ONCE_NOCHECK()
Date: Tue, 29 Mar 2022 14:39:43 +0200 [thread overview]
Message-ID: <20220329124017.737571-15-glider@google.com> (raw)
In-Reply-To: <20220329124017.737571-1-glider@google.com>
kmsan_init() is a macro that takes a possibly uninitialized value and
returns an initialized value of the same type. It can be used e.g. in
cases when a value comes from non-instrumented code to avoid false
positive reports.
In particular, we use kmsan_init() in READ_ONCE_NOCHECK() so that it
returns initialized values. This helps defeat false positives e.g. from
leftover stack contents accessed by stack unwinders.
Signed-off-by: Alexander Potapenko <glider@google.com>
---
Link: https://linux-review.googlesource.com/id/Icd1260073666f944922f031bfb6762379ba1fa38
---
include/asm-generic/rwonce.h | 5 +++--
include/linux/kmsan-checks.h | 40 ++++++++++++++++++++++++++++++++++++
mm/kmsan/Makefile | 5 ++++-
mm/kmsan/annotations.c | 28 +++++++++++++++++++++++++
4 files changed, 75 insertions(+), 3 deletions(-)
create mode 100644 mm/kmsan/annotations.c
diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h
index 8d0a6280e9824..7cf993af8e1ea 100644
--- a/include/asm-generic/rwonce.h
+++ b/include/asm-generic/rwonce.h
@@ -25,6 +25,7 @@
#include <linux/compiler_types.h>
#include <linux/kasan-checks.h>
#include <linux/kcsan-checks.h>
+#include <linux/kmsan-checks.h>
/*
* Yes, this permits 64-bit accesses on 32-bit architectures. These will
@@ -69,14 +70,14 @@ unsigned long __read_once_word_nocheck(const void *addr)
/*
* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a
- * word from memory atomically but without telling KASAN/KCSAN. This is
+ * word from memory atomically but without telling KASAN/KCSAN/KMSAN. This is
* usually used by unwinding code when walking the stack of a running process.
*/
#define READ_ONCE_NOCHECK(x) \
({ \
compiletime_assert(sizeof(x) == sizeof(unsigned long), \
"Unsupported access size for READ_ONCE_NOCHECK()."); \
- (typeof(x))__read_once_word_nocheck(&(x)); \
+ kmsan_init((typeof(x))__read_once_word_nocheck(&(x))); \
})
static __no_kasan_or_inline
diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h
index a6522a0c28df9..ecd8336190fc0 100644
--- a/include/linux/kmsan-checks.h
+++ b/include/linux/kmsan-checks.h
@@ -14,6 +14,44 @@
#ifdef CONFIG_KMSAN
+/*
+ * Helper functions that mark the return value initialized.
+ * See mm/kmsan/annotations.c.
+ */
+u8 kmsan_init_1(u8 value);
+u16 kmsan_init_2(u16 value);
+u32 kmsan_init_4(u32 value);
+u64 kmsan_init_8(u64 value);
+
+static inline void *kmsan_init_ptr(void *ptr)
+{
+ return (void *)kmsan_init_8((u64)ptr);
+}
+
+static inline char kmsan_init_char(char value)
+{
+ return (u8)kmsan_init_1((u8)value);
+}
+
+#define __decl_kmsan_init_type(type, fn) unsigned type : fn, signed type : fn
+
+/**
+ * kmsan_init - Make the value initialized.
+ * @val: 1-, 2-, 4- or 8-byte integer that may be treated as uninitialized by
+ * KMSAN.
+ *
+ * Return: value of @val that KMSAN treats as initialized.
+ */
+#define kmsan_init(val) \
+ ( \
+ (typeof(val))(_Generic((val), \
+ __decl_kmsan_init_type(char, kmsan_init_1), \
+ __decl_kmsan_init_type(short, kmsan_init_2), \
+ __decl_kmsan_init_type(int, kmsan_init_4), \
+ __decl_kmsan_init_type(long, kmsan_init_8), \
+ char : kmsan_init_char, \
+ void * : kmsan_init_ptr)(val)))
+
/**
* kmsan_poison_memory() - Mark the memory range as uninitialized.
* @address: address to start with.
@@ -48,6 +86,8 @@ void kmsan_check_memory(const void *address, size_t size);
#else
+#define kmsan_init(value) (value)
+
static inline void kmsan_poison_memory(const void *address, size_t size,
gfp_t flags)
{
diff --git a/mm/kmsan/Makefile b/mm/kmsan/Makefile
index a80dde1de7048..73b705cbf75b9 100644
--- a/mm/kmsan/Makefile
+++ b/mm/kmsan/Makefile
@@ -1,9 +1,11 @@
-obj-y := core.o instrumentation.o hooks.o report.o shadow.o
+obj-y := core.o instrumentation.o hooks.o report.o shadow.o annotations.o
KMSAN_SANITIZE := n
KCOV_INSTRUMENT := n
UBSAN_SANITIZE := n
+KMSAN_SANITIZE_kmsan_annotations.o := y
+
# Disable instrumentation of KMSAN runtime with other tools.
CC_FLAGS_KMSAN_RUNTIME := -fno-stack-protector
CC_FLAGS_KMSAN_RUNTIME += $(call cc-option,-fno-conserve-stack)
@@ -11,6 +13,7 @@ CC_FLAGS_KMSAN_RUNTIME += -DDISABLE_BRANCH_PROFILING
CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
+CFLAGS_annotations.o := $(CC_FLAGS_KMSAN_RUNTIME)
CFLAGS_core.o := $(CC_FLAGS_KMSAN_RUNTIME)
CFLAGS_hooks.o := $(CC_FLAGS_KMSAN_RUNTIME)
CFLAGS_instrumentation.o := $(CC_FLAGS_KMSAN_RUNTIME)
diff --git a/mm/kmsan/annotations.c b/mm/kmsan/annotations.c
new file mode 100644
index 0000000000000..8ccde90bcd12b
--- /dev/null
+++ b/mm/kmsan/annotations.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KMSAN annotations.
+ *
+ * The kmsan_init_SIZE functions reside in a separate translation unit to
+ * prevent inlining them. Clang may inline functions marked with
+ * __no_sanitize_memory attribute into functions without it, which effectively
+ * results in ignoring the attribute.
+ *
+ * Copyright (C) 2017-2022 Google LLC
+ * Author: Alexander Potapenko <glider@google.com>
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/kmsan-checks.h>
+
+#define DECLARE_KMSAN_INIT(size, t) \
+ __no_sanitize_memory t kmsan_init_##size(t value) \
+ { \
+ return value; \
+ } \
+ EXPORT_SYMBOL(kmsan_init_##size)
+
+DECLARE_KMSAN_INIT(1, u8);
+DECLARE_KMSAN_INIT(2, u16);
+DECLARE_KMSAN_INIT(4, u32);
+DECLARE_KMSAN_INIT(8, u64);
--
2.35.1.1021.g381101b075-goog
next prev parent reply other threads:[~2022-03-29 12:42 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-29 12:39 [PATCH v2 00/48] Add KernelMemorySanitizer infrastructure Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 01/48] x86: add missing include to sparsemem.h Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 02/48] stackdepot: reserve 5 extra bits in depot_stack_handle_t Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 03/48] kasan: common: adapt to the new prototype of __stack_depot_save() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 04/48] instrumented.h: allow instrumenting both sides of copy_from_user() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 05/48] x86: asm: instrument usercopy in get_user() and __put_user_size() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 06/48] asm-generic: instrument usercopy in cacheflush.h Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 07/48] kmsan: add ReST documentation Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 08/48] kmsan: introduce __no_sanitize_memory and __no_kmsan_checks Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 09/48] kmsan: mark noinstr as __no_sanitize_memory Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 10/48] x86: kmsan: pgtable: reduce vmalloc space Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 11/48] libnvdimm/pfn_dev: increase MAX_STRUCT_PAGE_SIZE Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 12/48] kcsan: clang: retire CONFIG_KCSAN_KCOV_BROKEN Alexander Potapenko
2022-03-30 6:00 ` Marco Elver
2022-03-29 12:39 ` [PATCH v2 13/48] kmsan: add KMSAN runtime core Alexander Potapenko
2022-03-30 8:58 ` Peter Zijlstra
2022-03-30 9:41 ` Peter Zijlstra
2022-04-04 14:39 ` Alexander Potapenko
2022-03-29 12:39 ` Alexander Potapenko [this message]
2022-03-29 12:39 ` [PATCH v2 15/48] kmsan: disable instrumentation of unsupported common kernel code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 16/48] MAINTAINERS: add entry for KMSAN Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 17/48] kmsan: mm: maintain KMSAN metadata for page operations Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 18/48] kmsan: mm: call KMSAN hooks from SLUB code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 19/48] kmsan: handle task creation and exiting Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 20/48] kmsan: init: call KMSAN initialization routines Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 21/48] instrumented.h: add KMSAN support Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 22/48] kmsan: unpoison @tlb in arch_tlb_gather_mmu() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 23/48] kmsan: add iomap support Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 24/48] Input: libps2: mark data received in __ps2_command() as initialized Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 25/48] kmsan: dma: unpoison DMA mappings Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 26/48] kmsan: virtio: check/unpoison scatterlist in vring_map_one_sg() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 27/48] kmsan: handle memory sent to/from USB Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 28/48] kmsan: instrumentation.h: add instrumentation_begin_with_regs() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 29/48] kmsan: entry: handle register passing from uninstrumented code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 30/48] kmsan: add tests for KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 31/48] kernel: kmsan: don't instrument stacktrace.c Alexander Potapenko
2022-04-04 14:56 ` Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 32/48] kmsan: disable strscpy() optimization under KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 33/48] crypto: kmsan: disable accelerated configs " Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 34/48] kmsan: disable physical page merging in biovec Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 35/48] kmsan: block: skip bio block merging logic for KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 36/48] kmsan: kcov: unpoison area->list in kcov_remote_area_put() Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 37/48] security: kmsan: fix interoperability with auto-initialization Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 38/48] objtool: kmsan: list KMSAN API functions as uaccess-safe Alexander Potapenko
2022-03-30 8:46 ` Peter Zijlstra
[not found] ` <CAG_fn=UzshCuwbq7pZ93v7+eVUgFq1dZ4L_9nEWhYnotmyZtJg@mail.gmail.com>
2022-04-14 15:38 ` Peter Zijlstra
2022-03-29 12:40 ` [PATCH v2 39/48] x86: kmsan: make READ_ONCE_TASK_STACK() return initialized values Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 40/48] x86: kmsan: disable instrumentation of unsupported code Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 41/48] x86: kmsan: skip shadow checks in __switch_to() Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 42/48] x86: kmsan: handle open-coded assembly in lib/iomem.c Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 43/48] x86: kmsan: use __msan_ string functions where possible Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 44/48] x86: kmsan: sync metadata pages on page fault Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 45/48] x86: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 46/48] x86: fs: kmsan: disable CONFIG_DCACHE_WORD_ACCESS Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 47/48] x86: kmsan: handle register passing from uninstrumented code Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 48/48] x86: kmsan: enable KMSAN builds for x86 Alexander Potapenko
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