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[Bug sanitizer/65435] UBsan runtime error reports in OpenSSL aes_core.c
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 16 Mar 2015 11:37:36 +0000
- Subject: [Bug sanitizer/65435] UBsan runtime error reports in OpenSSL aes_core.c
- Auto-submitted: auto-generated
- References: <bug-65435-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65435
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
OpenSSL of course. 136 << 24 is not representable in int.
This is undefined behavior in C99/C11, and defined behavior in C++11.
Quoting C99 6.5.7/4:
"The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are
filled with zeros. If E1 has an unsigned type, the value of the result is E1 Ã
2 ^ E2, reduced modulo one more than the maximum value representable in the
result type. If E1 has a signed type and nonnegative value, and E1 Ã 2 ^ E2 is
representable in the result type, then that is the resulting value; otherwise,
the behavior is undefined."