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[PATCH] Fix two undefined behaviors in gcc sources
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 21 Mar 2014 21:30:25 +0100
- Subject: [PATCH] Fix two undefined behaviors in gcc sources
- Authentication-results: sourceware.org; auth=none
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
--with-build-config=bootstrap-ubsan on i686-linux showed
most often these two issues.
The first one is that 32-bit signed time_t is multiplied by 1000, which
overflows the int type. The result is then cast to unsigned, so even on
64-bit hosts we don't care about the upper bits.
The other change fixes a badly written portable rotate, which was shitfing
up (correctly) by 0 for i == 0, but for all other i values was shifting up
64-bit value by 64.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2014-03-21 Jakub Jelinek <jakub@redhat.com>
* toplev.c (init_local_tick): Avoid signed integer multiplication
overflow.
* genautomata.c (reserv_sets_hash_value): Fix rotate idiom, avoid
shift by first operand's bitsize.
--- gcc/toplev.c.jj 2014-01-08 10:23:22.000000000 +0100
+++ gcc/toplev.c 2014-03-21 11:32:25.929893013 +0100
@@ -261,7 +261,7 @@ init_local_tick (void)
struct timeval tv;
gettimeofday (&tv, NULL);
- local_tick = tv.tv_sec * 1000 + tv.tv_usec / 1000;
+ local_tick = (unsigned) tv.tv_sec * 1000 + tv.tv_usec / 1000;
}
#else
{
--- gcc/genautomata.c.jj 2014-02-12 08:33:34.000000000 +0100
+++ gcc/genautomata.c 2014-03-21 12:01:14.245727924 +0100
@@ -3494,7 +3494,7 @@ reserv_sets_hash_value (reserv_sets_t re
{
reservs_num--;
hash_value += ((*reserv_ptr >> i)
- | (*reserv_ptr << ((sizeof (set_el_t) * CHAR_BIT) & -i)));
+ | (*reserv_ptr << (((sizeof (set_el_t) * CHAR_BIT) - 1) & -i)));
i++;
if (i == sizeof (set_el_t) * CHAR_BIT)
i = 0;
Jakub