Commit 3429055f authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton
Browse files

mm: kmsan: implement kmsan_memmove() 

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: default avatarAlexander Potapenko <glider@google.com>
Suggested-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: default avatarMarco 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 212f863f

include/linux/kmsan-checks.h

+15 −0
Original line number Diff line number Diff line
@@ -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 */

mm/kmsan/hooks.c

+11 −0
Original line number Diff line number Diff line
@@ -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)

{