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authorGeorge Popescu <georgepope@android.com>2020-10-15 20:13:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-16 11:11:22 -0700
commit6a6155f664e31c9be43cd690541a9a682ba3dc22 (patch)
treeaefade86b74d129bd319a46ddc9241dd56d61cf3
parent5cf53f3ce3b9ff5321b56f9ed9d90d59307be7d0 (diff)
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang
When the kernel is compiled with Clang, -fsanitize=bounds expands to -fsanitize=array-bounds and -fsanitize=local-bounds. Enabling -fsanitize=local-bounds with Clang has the unfortunate side-effect of inserting traps; this goes back to its original intent, which was as a hardening and not a debugging feature [1]. The same feature made its way into -fsanitize=bounds, but the traps remained. For that reason, -fsanitize=bounds was split into 'array-bounds' and 'local-bounds' [2]. Since 'local-bounds' doesn't behave like a normal sanitizer, enable it with Clang only if trapping behaviour was requested by CONFIG_UBSAN_TRAP=y. Add the UBSAN_BOUNDS_LOCAL config to Kconfig.ubsan to enable the 'local-bounds' option by default when UBSAN_TRAP is enabled. [1] http://lists.llvm.org/pipermail/llvm-dev/2012-May/049972.html [2] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20131021/091536.html Suggested-by: Marco Elver <elver@google.com> Signed-off-by: George Popescu <georgepope@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Brazdil <dbrazdil@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lkml.kernel.org/r/20200922074330.2549523-1-georgepope@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/Kconfig.ubsan14
-rw-r--r--scripts/Makefile.ubsan10
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 774315de555a..58f8d03d037b 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -47,6 +47,20 @@ config UBSAN_BOUNDS
to the {str,mem}*cpy() family of functions (that is addressed
by CONFIG_FORTIFY_SOURCE).
+config UBSAN_LOCAL_BOUNDS
+ bool "Perform array local bounds checking"
+ depends on UBSAN_TRAP
+ depends on CC_IS_CLANG
+ depends on !UBSAN_KCOV_BROKEN
+ help
+ This option enables -fsanitize=local-bounds which traps when an
+ exception/error is detected. Therefore, it should be enabled only
+ if trapping is expected.
+ Enabling this option detects errors due to accesses through a
+ pointer that is derived from an object of a statically-known size,
+ where an added offset (which may not be known statically) is
+ out-of-bounds.
+
config UBSAN_MISC
bool "Enable all other Undefined Behavior sanity checks"
default UBSAN
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 27348029b2b8..4e3fff0745e8 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -4,7 +4,15 @@ ifdef CONFIG_UBSAN_ALIGNMENT
endif
ifdef CONFIG_UBSAN_BOUNDS
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
+ ifdef CONFIG_CC_IS_CLANG
+ CFLAGS_UBSAN += -fsanitize=array-bounds
+ else
+ CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
+ endif
+endif
+
+ifdef CONFIG_UBSAN_LOCAL_BOUNDS
+ CFLAGS_UBSAN += -fsanitize=local-bounds
endif
ifdef CONFIG_UBSAN_MISC