Author: pfg
Date: Sat Oct 28 20:09:34 2017
New Revision: 325066
URL: https://svnweb.freebsd.org/changeset/base/325066
Log:
Fix out-of-bounds read in libc/regex.
The bug is an out-of-bounds read detected with address sanitizer that
happens when 'sp' in p_b_coll_elems() includes NUL byte[s], e.g. if it's
equal to "GS\x00". In that case len will be equal to 4, and the
strncmp(cp->name, sp, len) call will succeed when cp->name is "GS" but the
cp->name[len] == '\0' comparison will cause the read to go out-of-bounds.
Checking the length using strlen() instead eliminates the issue.
The bug was found in LLVM with oss-fuzz:
https://reviews.llvm.org/D39380
MFC after: 1 week
Obtained from: Vlad Tsyrklevich through posting on openbsd-tech
Modified:
head/lib/libc/regex/regcomp.c
Modified: head/lib/libc/regex/regcomp.c
==============================================================================
--- head/lib/libc/regex/regcomp.c Sat Oct 28 20:03:29 2017
(r325065)
+++ head/lib/libc/regex/regcomp.c Sat Oct 28 20:09:34 2017
(r325066)
@@ -1059,7 +1059,7 @@ p_b_coll_elem(struct parse *p,
}
len = p->next - sp;
for (cp = cnames; cp->name != NULL; cp++)
- if (strncmp(cp->name, sp, len) == 0 && cp->name[len] == '\0')
+ if (strncmp(cp->name, sp, len) == 0 && strlen(cp->name) == len)
return(cp->code); /* known name */
memset(&mbs, 0, sizeof(mbs));
if ((clen = mbrtowc(&wc, sp, len, &mbs)) == len)
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