Commit ce3ba2af authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Dave Hansen
Browse files

x86: Suppress KMSAN reports in arch_within_stack_frames() 



arch_within_stack_frames() performs stack walking and may confuse
KMSAN by stepping on stale shadow values. To prevent false positive
reports, disable KMSAN checks in this function.

This fixes KMSAN's interoperability with CONFIG_HARDENED_USERCOPY.

Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Tested-by: default avatarEric Biggers <ebiggers@google.com>
Link: https://github.com/google/kmsan/issues/89
Link: https://lore.kernel.org/lkml/Y3b9AAEKp2Vr3e6O@sol.localdomain/
Link: https://lore.kernel.org/all/20221118172305.3321253-1-glider%40google.com
parent 6be9a8f1

arch/x86/include/asm/thread_info.h

+5 −0
Original line number Diff line number Diff line
@@ -163,7 +163,12 @@ struct thread_info { 
 *	GOOD_FRAME	if within a frame

 *	BAD_STACK	if placed across a frame boundary (or outside stack)

 *	NOT_STACK	unable to determine (no frame pointers, etc)

 *

 * This function reads pointers from the stack and dereferences them. The

 * pointers may not have their KMSAN shadow set up properly, which may result

 * in false positive reports. Disable instrumentation to avoid those.

 */

__no_kmsan_checks

static inline int arch_within_stack_frames(const void * const stack,

					   const void * const stackend,

					   const void *obj, unsigned long len)