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| author | Arnd Bergmann <arnd@arndb.de> | 2026-03-06 16:05:49 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-04-05 13:53:19 -0700 |
| commit | d7651089939bf00fe033845e662905ce750b1f18 (patch) | |
| tree | 2ad33ce8e79af5ffac6cde4b0ce23f26dacb5eda /lib | |
| parent | db359fccf212e7fa3136e6edbed6228475646fd7 (diff) | |
| download | lwn-d7651089939bf00fe033845e662905ce750b1f18.tar.gz lwn-d7651089939bf00fe033845e662905ce750b1f18.zip | |
ubsan: turn off kmsan inside of ubsan instrumentation
The structure initialization in the two type mismatch handling functions
causes a call to __msan_memset() to be generated inside of a UACCESS
block, which in turn leads to an objtool warning about possibly leaking
uaccess-enabled state:
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch+0xda: call to __msan_memset() with UACCESS enabled
lib/ubsan.o: warning: objtool: __ubsan_handle_type_mismatch_v1+0xf4: call to __msan_memset() with UACCESS enabled
Most likely __msan_memset() is safe to be called here and could be added
to the uaccess_safe_builtin[] list of safe functions, but seeing that the
ubsan file itself already has kasan, ubsan and kcsan disabled itself, it
is probably a good idea to also turn off kmsan here, in particular this
also avoids the risk of recursing between ubsan and kcsan checks in other
functions of this file.
I saw this happen while testing randconfig builds with clang-22, but did
not try older versions, or attempt to see which kernel change introduced
the warning.
Link: https://lkml.kernel.org/r/20260306150613.350029-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile index 1b9ee167517f..ce3ae929ae8c 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -307,6 +307,7 @@ obj-$(CONFIG_UBSAN) += ubsan.o UBSAN_SANITIZE_ubsan.o := n KASAN_SANITIZE_ubsan.o := n KCSAN_SANITIZE_ubsan.o := n +KMSAN_SANITIZE_ubsan.o := n CFLAGS_ubsan.o := -fno-stack-protector $(DISABLE_KSTACK_ERASE) obj-$(CONFIG_SBITMAP) += sbitmap.o |