Messages in this thread |  | | Date | Thu, 21 Oct 2021 01:43:09 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] compiler-gcc.h: Define __SANITIZE_ADDRESS__ under hwaddress sanitizer |
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On Thu, Oct 21, 2021 at 08:00:00AM +0200, Marco Elver wrote: > On Wed, 20 Oct 2021 at 22:00, Kees Cook <keescook@chromium.org> wrote: > > When Clang is using the hwaddress sanitizer, it sets __SANITIZE_ADDRESS__ > > explicitly: > > > > #if __has_feature(address_sanitizer) || __has_feature(hwaddress_sanitizer) > > /* Emulate GCC's __SANITIZE_ADDRESS__ flag */ > > #define __SANITIZE_ADDRESS__ > > #endif > > Hmm, the comment is a little inaccurate if hwaddress sanitizer is on, > but I certainly wouldn't want compiler-clang.h to start emulating gcc > here and start defining __SANITIZE_HWADDRESS__ if the places where we > check it are the same as __SANITIZE_ADDRESS__. So this patch is the > right approach.
Yeah, I agree. I think that was Arnd's thinking as well.
> > > Once hwaddress sanitizer was added to GCC, however, a separate define > > was created, __SANITIZE_HWADDRESS__. The kernel is expecting to find > > __SANITIZE_ADDRESS__ in either case, though, and the existing string > > macros break on supported architectures: > > > > #if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \ > > !defined(__SANITIZE_ADDRESS__) > > > > where as other architectures (like arm32) have no idea about hwaddress > > sanitizer and just check for __SANITIZE_ADDRESS__: > > > > #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) > > arm32 doesn't support KASAN_SW_TAGS, so I think the bit about arm32 is > irrelevant.
Right -- I had just picked an example.
> Only arm64 can, and the reason that arm64 doesn't check against > "defined(CONFIG_KASAN)" is because we also have KASAN_HW_TAGS (no > compiler instrumentation). > > > This would lead to compiler foritfy self-test warnings when building > > with CONFIG_KASAN_SW_TAGS=y: > > > > warning: unsafe memmove() usage lacked '__read_overflow2' symbol in lib/test_fortify/read_overflow2-memmove.c > > warning: unsafe memcpy() usage lacked '__write_overflow' symbol in lib/test_fortify/write_overflow-memcpy.c > > ... > > > > Sort this out by also defining __SANITIZE_ADDRESS__ in GCC under the > > hwaddress sanitizer. > > > > Suggested-by: Arnd Bergmann <arnd@arndb.de> > > Cc: Nathan Chancellor <nathan@kernel.org> > > Cc: Nick Desaulniers <ndesaulniers@google.com> > > Cc: Miguel Ojeda <ojeda@kernel.org> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Marco Elver <elver@google.com> > > Cc: Will Deacon <will@kernel.org> > > Cc: Arvind Sankar <nivedita@alum.mit.edu> > > Cc: Masahiro Yamada <masahiroy@kernel.org> > > Cc: llvm@lists.linux.dev > > Signed-off-by: Kees Cook <keescook@chromium.org> > > Other than that, > > Reviewed-by: Marco Elver <elver@google.com>
Thanks! (Oh, BTW, it seems "b4" won't include your Reviewed-by: tag if it is indented like this.)
-Kees
-- Kees Cook
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