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 <ryabinin.a.a@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bug: 199373673
(cherry picked from commit 6aaa31aeb9cf260e1b7155cc11ec864f052db5ec)
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Change-Id: I7f0e9d7a4d7c69c21e42bd21070c5d265bddbff1
71f70987f9