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From:   Kees Cook <keescook@chromium.org>
To:     Miguel Ojeda <ojeda@kernel.org>
Cc:     Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Marco Elver <elver@google.com>, Will Deacon <will@kernel.org>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Masahiro Yamada <masahiroy@kernel.org>, llvm@lists.linux.dev,
        Ard Biesheuvel <ardb@kernel.org>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH] compiler-gcc.h: Define __SANITIZE_ADDRESS__ under hwaddress sanitizer
Date:   Wed, 20 Oct 2021 13:00:39 -0700
Message-Id: <20211020200039.170424-1-keescook@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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

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__)

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>
---
I'm intending to take this via my overflow series, since that is what introduces
the compile-test regression tests (which found this legitimate bug). :)

-Kees
---
 include/linux/compiler-gcc.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 6f24eb8c5dda..ccbbd31b3aae 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -121,6 +121,14 @@
 #define __no_sanitize_coverage
 #endif
 
+/*
+ * Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel,
+ * matching the defines used by Clang.
+ */
+#ifdef __SANITIZE_HWADDRESS__
+#define __SANITIZE_ADDRESS__
+#endif
+
 /*
  * Turn individual warnings and errors on and off locally, depending
  * on version.
-- 
2.30.2