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authorKees Cook <keescook@chromium.org>2024-01-18 15:06:05 -0800
committerKees Cook <keescook@chromium.org>2024-02-20 20:44:49 -0800
commit557f8c582a9ba8abe6aa0fd734b6f342af106b26 (patch)
tree6644df0a1d37b46be67f234d27b11d7f58067446 /scripts/Makefile.lib
parent918327e9b7ffb45321cbb4b9b86b58ec555fe6b3 (diff)
ubsan: Reintroduce signed overflow sanitizer
In order to mitigate unexpected signed wrap-around[1], bring back the signed integer overflow sanitizer. It was removed in commit 6aaa31aeb9cf ("ubsan: remove overflow checks") because it was effectively a no-op when combined with -fno-strict-overflow (which correctly changes signed overflow from being "undefined" to being explicitly "wrap around"). Compilers are adjusting their sanitizers to trap wrap-around and to detecting common code patterns that should not be instrumented (e.g. "var + offset < var"). Prepare for this and explicitly rename the option from "OVERFLOW" to "WRAP" to more accurately describe the behavior. To annotate intentional wrap-around arithmetic, the helpers wrapping_add/sub/mul_wrap() can be used for individual statements. At the function level, the __signed_wrap attribute can be used to mark an entire function as expecting its signed arithmetic to wrap around. For a single object file the Makefile can use "UBSAN_SIGNED_WRAP_target.o := n" to mark it as wrapping, and for an entire directory, "UBSAN_SIGNED_WRAP := n" can be used. Additionally keep these disabled under CONFIG_COMPILE_TEST for now. Link: https://github.com/KSPP/linux/issues/26 [1] Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Hao Luo <haoluo@google.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Justin Stitt <justinstitt@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'scripts/Makefile.lib')
-rw-r--r--scripts/Makefile.lib3
1 files changed, 3 insertions, 0 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 52efc520ae4f..b4a248c20654 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -177,6 +177,9 @@ ifeq ($(CONFIG_UBSAN),y)
_c_flags += $(if $(patsubst n%,, \
$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)y), \
$(CFLAGS_UBSAN))
+_c_flags += $(if $(patsubst n%,, \
+ $(UBSAN_SIGNED_WRAP_$(basetarget).o)$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SIGNED_WRAP)$(UBSAN_SANITIZE)y), \
+ $(CFLAGS_UBSAN_SIGNED_WRAP))
endif
ifeq ($(CONFIG_KCOV),y)