On Wed, 20 Mar 2024 at 11:18, Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > 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@xxxxxxxxxxxxxxxxxxx/ > Suggested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Marco Elver <elver@xxxxxxxxxx> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> > --- > include/linux/kmsan-checks.h | 15 +++++++++++++++ > mm/kmsan/hooks.c | 11 +++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h > index c4cae333deec5..e1082dc40abc2 100644 > --- a/include/linux/kmsan-checks.h > +++ b/include/linux/kmsan-checks.h > @@ -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 */ > diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c > index 5d6e2dee5692a..364f778ee226d 100644 > --- a/mm/kmsan/hooks.c > +++ b/mm/kmsan/hooks.c > @@ -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) > { > -- > 2.44.0.291.gc1ea87d7ee-goog >
