diff options
| author | Alexander Potapenko <glider@google.com> | 2022-11-28 10:45:41 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-12-11 18:12:11 -0800 |
| commit | 85716a80c16dd6b6d1aaed87cd4b91c9b1d9b9b2 (patch) | |
| tree | 903afb31d5696113fb7901bb70fd57a834f67e12 /mm/kmsan | |
| parent | 1e8e4a7cc2fa3017b1daf02612e095d51924ce1e (diff) | |
kmsan: allow using __msan_instrument_asm_store() inside runtime
In certain cases (e.g. when handling a softirq)
__msan_instrument_asm_store(&var, sizeof(var)) may be called with from
within KMSAN runtime, but later the value of @var is used with
!kmsan_in_runtime(), leading to false positives.
Because kmsan_internal_unpoison_memory() doesn't take locks, it should be
fine to call it without kmsan_in_runtime() checks, which fixes the
mentioned false positives.
Link: https://lkml.kernel.org/r/20221128094541.2645890-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/kmsan')
| -rw-r--r-- | mm/kmsan/instrumentation.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/kmsan/instrumentation.c b/mm/kmsan/instrumentation.c index 271f135f97a1..770fe02904f3 100644 --- a/mm/kmsan/instrumentation.c +++ b/mm/kmsan/instrumentation.c @@ -81,12 +81,16 @@ DECLARE_METADATA_PTR_GETTER(8); * Handle a memory store performed by inline assembly. KMSAN conservatively * attempts to unpoison the outputs of asm() directives to prevent false * positives caused by missed stores. + * + * __msan_instrument_asm_store() may be called for inline assembly code when + * entering or leaving IRQ. We omit the check for kmsan_in_runtime() to ensure + * the memory written to in these cases is also marked as initialized. */ void __msan_instrument_asm_store(void *addr, uintptr_t size) { unsigned long ua_flags; - if (!kmsan_enabled || kmsan_in_runtime()) + if (!kmsan_enabled) return; ua_flags = user_access_save(); @@ -103,10 +107,8 @@ void __msan_instrument_asm_store(void *addr, uintptr_t size) user_access_restore(ua_flags); return; } - kmsan_enter_runtime(); /* Unpoisoning the memory on best effort. */ kmsan_internal_unpoison_memory(addr, size, /*checked*/ false); - kmsan_leave_runtime(); user_access_restore(ua_flags); } EXPORT_SYMBOL(__msan_instrument_asm_store); |