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@xxxxxxxxxxxxxxxxxxx/ Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> --- v2: fix a copypasto in a comment spotted by Linus --- include/linux/instrumented.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h index 1b608e00290aa..711a1f0d1a735 100644 --- a/include/linux/instrumented.h +++ b/include/linux/instrumented.h @@ -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 -- 2.44.0.291.gc1ea87d7ee-goog
