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From: "shaohua.li at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/107893] gcc trunk at -O0 (UBSan) misses a
 Null-pointer-dereference
Date: Mon, 28 Nov 2022 09:05:25 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107893

--- Comment #4 from Li Shaohua <shaohua.li at inf dot ethz.ch> ---
(In reply to Richard Biener from comment #3)
> That is,
>=20
> int main() {
>   int *a =3D 0;
>    (a[0] | a[1]) >> 056;
> }
>=20
> works at -O0:
>=20
> t.c:3:6: runtime error: load of null pointer of type 'int'

Yes, the a[1] access caused the segfault. For clang's UBsan, it emits an er=
ror
message for a[1]:

a.c:3:5: runtime error: applying non-zero offset 4 to null pointer
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior a.c:3:5 in


Is there a way for gcc's UBsan to warn such errors?=