Messages in this thread Patch in this message | | | Date | Mon, 18 Oct 2021 12:57:58 -0700 | From | Kees Cook <> | Subject | Re: [PATCH 2/2] kasan: use fortified strings for hwaddress sanitizer |
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On Wed, Oct 13, 2021 at 05:00:06PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > GCC has separate macros for -fsanitize=kernel-address and > -fsanitize=kernel-hwaddress, and the check in the arm64 string.h > gets this wrong, which leads to string functions not getting > fortified with gcc. The newly added tests find this: > > warning: unsafe memchr() usage lacked '__read_overflow' warning in /git/arm-soc/lib/test_fortify/read_overflow-memchr.c > warning: unsafe memchr_inv() usage lacked '__read_overflow' symbol in /git/arm-soc/lib/test_fortify/read_overflow-memchr_inv.c > warning: unsafe memcmp() usage lacked '__read_overflow' warning in /git/arm-soc/lib/test_fortify/read_overflow-memcmp.c > warning: unsafe memscan() usage lacked '__read_overflow' symbol in /git/arm-soc/lib/test_fortify/read_overflow-memscan.c > warning: unsafe memcmp() usage lacked '__read_overflow2' warning in /git/arm-soc/lib/test_fortify/read_overflow2-memcmp.c > warning: unsafe memcpy() usage lacked '__read_overflow2' symbol in /git/arm-soc/lib/test_fortify/read_overflow2-memcpy.c > warning: unsafe memmove() usage lacked '__read_overflow2' symbol in /git/arm-soc/lib/test_fortify/read_overflow2-memmove.c > warning: unsafe memcpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-memcpy.c > warning: unsafe memmove() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-memmove.c > warning: unsafe memset() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-memset.c > warning: unsafe strcpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strcpy-lit.c > warning: unsafe strcpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strcpy.c > warning: unsafe strlcpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strlcpy-src.c > warning: unsafe strlcpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strlcpy.c > warning: unsafe strncpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strncpy-src.c > warning: unsafe strncpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strncpy.c > warning: unsafe strscpy() usage lacked '__write_overflow' symbol in /git/arm-soc/lib/test_fortify/write_overflow-strscpy.c >
What is the build config that trips these warnings?
In trying to understand this, I see in arch/arm64/include/asm/string.h:
#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \ !defined(__SANITIZE_ADDRESS__)
other architectures (like arm32) do:
#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
so it's okay because it's not getting touched by the hwaddress sanitizer? e.g. I see:
config CC_HAS_KASAN_GENERIC def_bool $(cc-option, -fsanitize=kernel-address)
config CC_HAS_KASAN_SW_TAGS def_bool $(cc-option, -fsanitize=kernel-hwaddress)
> Add a workaround to include/linux/compiler_types.h so we always > define __SANITIZE_ADDRESS__ for either mode, as we already do > for clang.
Where is the clang work-around? (Or is this a statement that clang, under -fsanitize=kernel-hwaddress, already sets __SANITIZE_ADDRESS__ by default?
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/linux/compiler_types.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > index aad6f6408bfa..2f2776fffefe 100644 > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -178,6 +178,13 @@ struct ftrace_likely_data { > */ > #define noinline_for_stack noinline > > +/* > + * Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel > + */ > +#ifdef __SANITIZE_HWADDRESS__ > +#define __SANITIZE_ADDRESS__ > +#endif
Should this go into compiler-gcc.h instead?
> + > /* > * Sanitizer helper attributes: Because using __always_inline and > * __no_sanitize_* conflict, provide helper attributes that will either expand > -- > 2.29.2 >
-- Kees Cook
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