It turned out that KMSAN instruments READ_ONCE_NOCHECK(), resulting in false positive reports, because __no_sanitize_or_inline enforced inlining.

Properly declare __no_sanitize_or_inline under __SANITIZE_MEMORY__, so that it does not __always_inline the annotated function.

Reported-by: syzbot+355c5bb8c1445c871ee8@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/000000000000826ac1061675b0e3@google.com Fixes: 5de0ce85f5a4 ("kmsan: mark noinstr as __no_sanitize_memory") Cc: stable@vger.kernel.org Signed-off-by: Alexander Potapenko glider@google.com Reviewed-by: Marco Elver elver@google.com --- include/linux/compiler_types.h | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 0caf354cb94b5..a6a28952836cb 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -278,6 +278,17 @@ struct ftrace_likely_data { # define __no_kcsan #endif

+#ifdef __SANITIZE_MEMORY__ +/* + * Similarly to KASAN and KCSAN, KMSAN loses function attributes of inlined + * functions, therefore disabling KMSAN checks also requires disabling inlining. + * + * __no_sanitize_or_inline effectively prevents KMSAN from reporting errors + * within the function and marks all its outputs as initialized. + */ +# define __no_sanitize_or_inline __no_kmsan_checks notrace __maybe_unused +#endif + #ifndef __no_sanitize_or_inline #define __no_sanitize_or_inline __always_inline #endif