From d149fa4fd4e507b3bd3c2510157e1c6864c8f2d2 Mon Sep 17 00:00:00 2001 From: pfg Date: Sat, 4 Nov 2017 14:45:36 +0000 Subject: [PATCH] MFC r325066: 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 Obtained from: Vlad Tsyrklevich through posting on openbsd-tech git-svn-id: svn://svn.freebsd.org/base/stable/10@325394 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- lib/libc/regex/regcomp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/libc/regex/regcomp.c b/lib/libc/regex/regcomp.c index 1e231fb03..49479961b 100644 --- a/lib/libc/regex/regcomp.c +++ b/lib/libc/regex/regcomp.c @@ -922,7 +922,7 @@ 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) -- 2.42.0