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Avoid undefined behaviour in netgroupcache

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Using a buffer after it has been reallocated is undefined behaviour,
so get offsets of the triplets in the old buffer before reallocating
it.
This commit is contained in:
Siddhesh Poyarekar
2014-01-27 11:32:44 +05:30
parent 0c00f062dd
commit af37a8a349
2 changed files with 16 additions and 5 deletions
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16
nscd/netgroupcache.c
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@@ -241,15 +241,21 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
if (buflen - req->key_len - bufused < needed)
{
buflen += MAX (buflen, 2 * needed);
/* Save offset in the old buffer. We don't
bother with the NULL check here since
we'll do that later anyway. */
size_t nhostdiff = nhost - buffer;
size_t nuserdiff = nuser - buffer;
size_t ndomaindiff = ndomain - buffer;
char *newbuf = xrealloc (buffer, buflen);
/* Adjust the pointers in the new
/* Fix up the triplet pointers into the new
buffer. */
nhost = (nhost ? newbuf + (nhost - buffer)
nhost = (nhost ? newbuf + nhostdiff
: NULL);
nuser = (nuser ? newbuf + (nuser - buffer)
nuser = (nuser ? newbuf + nuserdiff
: NULL);
ndomain = (ndomain
? newbuf + (ndomain - buffer)
ndomain = (ndomain ? newbuf + ndomaindiff
: NULL);
buffer = newbuf;
}