From 6aaa31aeb9cf260e1b7155cc11ec864f052db5ec Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 25 Feb 2021 17:22:42 -0800 Subject: ubsan: remove overflow checks Since GCC 8.0 -fsanitize=signed-integer-overflow doesn't work with -fwrapv. -fwrapv makes signed overflows defines and GCC essentially disables ubsan checks. On GCC < 8.0 -fwrapv doesn't have influence on -fsanitize=signed-integer-overflow setting, so it kinda works but generates false-positves and violates uaccess rules: lib/iov_iter.o: warning: objtool: iovec_from_user()+0x22d: call to __ubsan_handle_add_overflow() with UACCESS enabled Disable signed overflow checks to avoid these problems. Remove unsigned overflow checks as well. Unsigned overflow appeared as side effect of commit cdf8a76fda4a ("ubsan: move cc-option tests into Kconfig"), but it never worked (kernel doesn't boot). And unsigned overflows are allowed by C standard, so it just pointless. Link: https://lkml.kernel.org/r/20210209232348.20510-1-ryabinin.a.a@gmail.com Signed-off-by: Andrey Ryabinin Acked-by: Peter Zijlstra (Intel) Cc: Josh Poimboeuf Cc: Randy Dunlap Cc: Stephen Rothwell Cc: Dmitry Vyukov Cc: Kees Cook Cc: Alexander Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/Kconfig.ubsan | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'lib/Kconfig.ubsan') diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 3a0b1c930733..e5372a13511d 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -112,23 +112,6 @@ config UBSAN_UNREACHABLE This option enables -fsanitize=unreachable which checks for control flow reaching an expected-to-be-unreachable position. -config UBSAN_SIGNED_OVERFLOW - bool "Perform checking for signed arithmetic overflow" - default UBSAN - depends on $(cc-option,-fsanitize=signed-integer-overflow) - help - This option enables -fsanitize=signed-integer-overflow which checks - for overflow of any arithmetic operations with signed integers. - -config UBSAN_UNSIGNED_OVERFLOW - bool "Perform checking for unsigned arithmetic overflow" - depends on $(cc-option,-fsanitize=unsigned-integer-overflow) - depends on !X86_32 # avoid excessive stack usage on x86-32/clang - help - This option enables -fsanitize=unsigned-integer-overflow which checks - for overflow of any arithmetic operations with unsigned integers. This - currently causes x86 to fail to boot. - config UBSAN_OBJECT_SIZE bool "Perform checking for accesses beyond the end of objects" default UBSAN -- cgit