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| author | Kees Cook <keescook@chromium.org> | 2024-01-18 15:06:05 -0800 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2024-02-20 20:44:49 -0800 |
| commit | 557f8c582a9ba8abe6aa0fd734b6f342af106b26 (patch) | |
| tree | 6644df0a1d37b46be67f234d27b11d7f58067446 /scripts | |
| parent | 918327e9b7ffb45321cbb4b9b86b58ec555fe6b3 (diff) | |
| download | linux-557f8c582a9ba8abe6aa0fd734b6f342af106b26.tar.gz | |
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')
| -rw-r--r-- | scripts/Makefile.lib | 3 | ||||
| -rw-r--r-- | scripts/Makefile.ubsan | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 52efc520ae4fa3..b4a248c20654f1 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) diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 7cf42231042b67..b2d3b273b8028c 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -13,3 +13,6 @@ ubsan-cflags-$(CONFIG_UBSAN_ENUM) += -fsanitize=enum ubsan-cflags-$(CONFIG_UBSAN_TRAP) += $(call cc-option,-fsanitize-trap=undefined,-fsanitize-undefined-trap-on-error) export CFLAGS_UBSAN := $(ubsan-cflags-y) + +ubsan-signed-wrap-cflags-$(CONFIG_UBSAN_SIGNED_WRAP) += -fsanitize=signed-integer-overflow +export CFLAGS_UBSAN_SIGNED_WRAP := $(ubsan-signed-wrap-cflags-y) |