Clang 15 will provide an option to prefix calls to memcpy/memset/memmove
with __asan_ in instrumented functions: https://reviews.llvm.org/D122724
GCC will add support in future:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108777
Use it to regain KASAN instrumentation of memcpy/memset/memmove on
architectures that require noinstr to be really free from instrumented
mem*() functions (all GENERIC_ENTRY architectures).
Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Marco Elver <[email protected]>
---
v3:
* Resend with actual fix.
v2:
* Use asan-kernel-mem-intrinsic-prefix=1, so that once GCC supports the
param, it also works there (it needs the =1).
The Fixes tag is just there to show the dependency, and that people
shouldn't apply this patch without 69d4c0d32186.
---
scripts/Makefile.kasan | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index b9e94c5e7097..3b35a88af60d 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -38,6 +38,13 @@ endif
CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable))
+ifdef CONFIG_GENERIC_ENTRY
+# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*()
+# instead. With compilers that don't support this option, compiler-inserted
+# memintrinsics won't be checked by KASAN.
+CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)
+endif
+
endif # CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_SW_TAGS
--
2.39.1.581.gbfd45094c4-goog
On Mon, Feb 13, 2023 at 09:13:35PM +0100, Marco Elver wrote:
> Clang 15 will provide an option to prefix calls to memcpy/memset/memmove
> with __asan_ in instrumented functions: https://reviews.llvm.org/D122724
>
> GCC will add support in future:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108777
>
> Use it to regain KASAN instrumentation of memcpy/memset/memmove on
> architectures that require noinstr to be really free from instrumented
> mem*() functions (all GENERIC_ENTRY architectures).
>
> Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> Signed-off-by: Marco Elver <[email protected]>
Thanks!
Acked-by: Peter Zijlstra (Intel) <[email protected]>
> ---
> v3:
> * Resend with actual fix.
>
> v2:
> * Use asan-kernel-mem-intrinsic-prefix=1, so that once GCC supports the
> param, it also works there (it needs the =1).
>
> The Fixes tag is just there to show the dependency, and that people
> shouldn't apply this patch without 69d4c0d32186.
> ---
> scripts/Makefile.kasan | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> index b9e94c5e7097..3b35a88af60d 100644
> --- a/scripts/Makefile.kasan
> +++ b/scripts/Makefile.kasan
> @@ -38,6 +38,13 @@ endif
>
> CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable))
>
> +ifdef CONFIG_GENERIC_ENTRY
> +# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*()
> +# instead. With compilers that don't support this option, compiler-inserted
> +# memintrinsics won't be checked by KASAN.
> +CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)
> +endif
> +
> endif # CONFIG_KASAN_GENERIC
>
> ifdef CONFIG_KASAN_SW_TAGS
> --
> 2.39.1.581.gbfd45094c4-goog
>