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authorUlrich Drepper <drepper@redhat.com>2010-05-06 04:42:46 -0700
committerUlrich Drepper <drepper@redhat.com>2010-05-06 04:42:46 -0700
commit5f24d53acb2cd02ffb4ac925c0244e4f1f854499 (patch)
tree003e29b340698e10773e68adc30f8dcf8f345b5a /malloc
parentd84acf388ed8b3f162dda0512139095bfc268beb (diff)
downloadglibc-5f24d53acb2cd02ffb4ac925c0244e4f1f854499.tar.gz
Fix race in free sanity check.
Diffstat (limited to 'malloc')
-rw-r--r--malloc/malloc.c15
1 files changed, 9 insertions, 6 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 722b1d4961..9594be4cbd 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4859,6 +4859,7 @@ _int_free(mstate av, mchunkptr p)
#ifdef ATOMIC_FASTBINS
mchunkptr fd;
mchunkptr old = *fb;
+ unsigned int old_idx = ~0u;
do
{
/* Another simple check: make sure the top of the bin is not the
@@ -4868,15 +4869,17 @@ _int_free(mstate av, mchunkptr p)
errstr = "double free or corruption (fasttop)";
goto errout;
}
- if (old != NULL
- && __builtin_expect (fastbin_index(chunksize(old)) != idx, 0))
- {
- errstr = "invalid fastbin entry (free)";
- goto errout;
- }
+ if (old != NULL)
+ old_idx = fastbin_index(chunksize(old));
p->fd = fd = old;
}
while ((old = catomic_compare_and_exchange_val_rel (fb, p, fd)) != fd);
+
+ if (fd != NULL && __builtin_expect (old_idx != idx, 0))
+ {
+ errstr = "invalid fastbin entry (free)";
+ goto errout;
+ }
#else
/* Another simple check: make sure the top of the bin is not the
record we are going to add (i.e., double free). */