On Wed, 20 Mar 2024 at 11:19, Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > 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> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> > --- > 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 >
