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mm: kmsan: implement kmsan_memmove()

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Provide a hook that can be used by custom memcpy implementations to tell
KMSAN that the metadata needs to be copied.  Without that, false positive
reports are possible in the cases where KMSAN fails to intercept memory
initialization.

Link: https://lore.kernel.org/all/3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp/
Link: https://lkml.kernel.org/r/20240320101851.2589698-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Potapenko 2024-03-20 11:18:49 +01:00 committed by Andrew Morton
parent 212f863fa8
commit 3429055f04
2 changed files with 26 additions and 0 deletions
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15
include/linux/kmsan-checks.h
View File

@ -61,6 +61,17 @@ void kmsan_check_memory(const void *address, size_t size);
void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
size_t left);
/**
* kmsan_memmove() - Notify KMSAN about a data copy within kernel.
* @to: destination address in the kernel.
* @from: source address in the kernel.
* @size: number of bytes to copy.
*
* Invoked after non-instrumented version (e.g. implemented using assembly
* code) of memmove()/memcpy() is called, in order to copy KMSAN's metadata.
*/
void kmsan_memmove(void *to, const void *from, size_t to_copy);
#else
static inline void kmsan_poison_memory(const void *address, size_t size,
@ -78,6 +89,10 @@ static inline void kmsan_copy_to_user(void __user *to, const void *from,
{
}
static inline void kmsan_memmove(void *to, const void *from, size_t to_copy)
{
}
#endif
#endif /* _LINUX_KMSAN_CHECKS_H */

11
mm/kmsan/hooks.c
View File

@ -285,6 +285,17 @@ void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
}
EXPORT_SYMBOL(kmsan_copy_to_user);
void kmsan_memmove(void *to, const void *from, size_t size)
{
if (!kmsan_enabled || kmsan_in_runtime())
return;
kmsan_enter_runtime();
kmsan_internal_memmove_metadata(to, (void *)from, size);
kmsan_leave_runtime();
}
EXPORT_SYMBOL(kmsan_memmove);
/* Helper function to check an URB. */
void kmsan_handle_urb(const struct urb *urb, bool is_out)
{