Author: jh
Date: Wed Mar 3 15:43:26 2010
New Revision: 204636
URL: http://svn.freebsd.org/changeset/base/204636
Log:
In reallocf(3), free the memory only when size != 0. Otherwise, when the
System V compatibility option (malloc "V" flag) is in effect a zero sized
reallocf() could cause a double free.
PR: bin/141753
Submitted by: Dan Lukes
Modified:
head/lib/libc/stdlib/reallocf.c
Modified: head/lib/libc/stdlib/reallocf.c
==============================================================================
--- head/lib/libc/stdlib/reallocf.c Wed Mar 3 15:05:58 2010
(r204635)
+++ head/lib/libc/stdlib/reallocf.c Wed Mar 3 15:43:26 2010
(r204636)
@@ -35,7 +35,14 @@ reallocf(void *ptr, size_t size)
void *nptr;
nptr = realloc(ptr, size);
- if (!nptr && ptr)
+
+ /*
+ * When the System V compatibility option (malloc "V" flag) is
+ * in effect, realloc(ptr, 0) frees the memory and returns NULL.
+ * So, to avoid double free, call free() only when size != 0.
+ * realloc(ptr, 0) can't fail when ptr != NULL.
+ */
+ if (!nptr && ptr && size != 0)
free(ptr);
return (nptr);
}
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