* [PATCH -tip v2] kasan: Emit different calls for instrumentable memintrinsics
@ 2023-02-13 20:10 Marco Elver
0 siblings, 0 replies; only message in thread
From: Marco Elver @ 2023-02-13 20:10 UTC (permalink / raw)
To: elver, Peter Zijlstra
Cc: Masahiro Yamada, Nathan Chancellor, Nick Desaulniers,
Nicolas Schier, Andrey Ryabinin, Alexander Potapenko,
Andrey Konovalov, Dmitry Vyukov, Vincenzo Frascino, linux-kbuild,
kasan-dev, linux-kernel, Ingo Molnar, Tony Lindgren, Ulf Hansson,
Jakub Jelinek, linux-toolchains
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 <elver@google.com>
---
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..78336b04c077 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)
+endif
+
endif # CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_SW_TAGS
--
2.39.1.581.gbfd45094c4-goog
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2023-02-13 20:10 [PATCH -tip v2] kasan: Emit different calls for instrumentable memintrinsics Marco Elver
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