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authorNick Desaulniers <ndesaulniers@google.com>2022-07-14 23:56:43 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-07-15 01:45:26 +0300
commite5d523f1ae8f2cef01f8e071aeee432654166708 (patch)
tree70882f76aadafb78cff39787cf8de945c0eed09b /lib
parentb926f2adb0442090351dc8321ec1f99b22e372da (diff)
downloadlinux-e5d523f1ae8f2cef01f8e071aeee432654166708.tar.xz
ubsan: disable UBSAN_DIV_ZERO for clang
Building with UBSAN_DIV_ZERO with clang produces numerous fallthrough warnings from objtool. In the case of uncheck division, UBSAN_DIV_ZERO may introduce new control flow to check for division by zero. Because the result of the division is undefined, LLVM may optimize the control flow such that after the call to __ubsan_handle_divrem_overflow doesn't matter. If panic_on_warn was set, __ubsan_handle_divrem_overflow would panic. The problem is is that panic_on_warn is run time configurable. If it's disabled, then we cannot guarantee that we will be able to recover safely. Disable this config for clang until we can come up with a solution in LLVM. Link: https://github.com/ClangBuiltLinux/linux/issues/1657 Link: https://github.com/llvm/llvm-project/issues/56289 Link: https://lore.kernel.org/lkml/CAHk-=wj1qhf7y3VNACEexyp5EbkNpdcu_542k-xZpzmYLOjiCg@mail.gmail.com/ Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.ubsan3
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index a9f7eb047768..fd15230a703b 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -84,6 +84,9 @@ config UBSAN_SHIFT
config UBSAN_DIV_ZERO
bool "Perform checking for integer divide-by-zero"
depends on $(cc-option,-fsanitize=integer-divide-by-zero)
+ # https://github.com/ClangBuiltLinux/linux/issues/1657
+ # https://github.com/llvm/llvm-project/issues/56289
+ depends on !CC_IS_CLANG
help
This option enables -fsanitize=integer-divide-by-zero which checks
for integer division by zero. This is effectively redundant with the