Commit 922621a6 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton
Browse files

instrumented.h: add instrument_memcpy_before, instrument_memcpy_after 

Bug detection tools based on compiler instrumentation may miss memory
accesses in custom memcpy implementations (such as copy_mc_to_kernel). 
Provide instrumentation hooks that tell KASAN, KCSAN, and KMSAN about such
accesses.

Link: https://lore.kernel.org/all/3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp/
Link: https://lkml.kernel.org/r/20240320101851.2589698-2-glider@google.com


Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3429055f

include/linux/instrumented.h

+35 −0
Original line number Diff line number Diff line
@@ -147,6 +147,41 @@ instrument_copy_from_user_after(const void *to, const void __user *from, 
	kmsan_unpoison_memory(to, n - left);

}



/**

 * instrument_memcpy_before - add instrumentation before non-instrumented memcpy

 * @to: destination address

 * @from: source address

 * @n: number of bytes to copy

 *

 * Instrument memory accesses that happen in custom memcpy implementations. The

 * instrumentation should be inserted before the memcpy call.

 */

static __always_inline void instrument_memcpy_before(void *to, const void *from,

						     unsigned long n)

{

	kasan_check_write(to, n);

	kasan_check_read(from, n);

	kcsan_check_write(to, n);

	kcsan_check_read(from, n);

}



/**

 * instrument_memcpy_after - add instrumentation after non-instrumented memcpy

 * @to: destination address

 * @from: source address

 * @n: number of bytes to copy

 * @left: number of bytes not copied (if known)

 *

 * Instrument memory accesses that happen in custom memcpy implementations. The

 * instrumentation should be inserted after the memcpy call.

 */

static __always_inline void instrument_memcpy_after(void *to, const void *from,

						    unsigned long n,

						    unsigned long left)

{

	kmsan_memmove(to, from, n - left);

}



/**

 * instrument_get_user() - add instrumentation to get_user()-like macros

 * @to: destination variable, may not be address-taken