Date: Sun, 8 Sep 2019 01:58:03 +0000 (UTC) From: Cy Schubert <cy@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r352027 - in stable: 11/lib/libc/nameser 12/lib/libc/nameser Message-ID: <201909080158.x881w3uQ068758@repo.freebsd.org>
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Author: cy Date: Sun Sep 8 01:58:02 2019 New Revision: 352027 URL: https://svnweb.freebsd.org/changeset/base/352027 Log: MFC r351889: Bounds check again after advancing cp, otherwise we have a possible heap buffer overflow. This was discovered by a Google fuzzer test. This can lead to remote denial of service. User interaction and execution privileges are not a prerequisite for exploitation. Reported by: enh at Google, to FreeBSD by maya@NetBSD.org Obtained from: enh at Google See also: NetBSD ns_name.c r1.12 Reviewed by: delphij, ume MFC after: 3 days https://android-review.googlesource.com/c/platform/bionic/+/1093130 Differential Revision: https://reviews.freebsd.org/D21523 Modified: stable/12/lib/libc/nameser/ns_name.c Directory Properties: stable/12/ (props changed) Changes in other areas also in this revision: Modified: stable/11/lib/libc/nameser/ns_name.c Directory Properties: stable/11/ (props changed) Modified: stable/12/lib/libc/nameser/ns_name.c ============================================================================== --- stable/12/lib/libc/nameser/ns_name.c Sat Sep 7 23:39:30 2019 (r352026) +++ stable/12/lib/libc/nameser/ns_name.c Sun Sep 8 01:58:02 2019 (r352027) @@ -684,7 +684,7 @@ ns_name_skip(const u_char **ptrptr, const u_char *eom) { const u_char *cp; u_int n; - int l; + int l = 0; cp = *ptrptr; while (cp < eom && (n = *cp++) != 0) { @@ -694,7 +694,7 @@ ns_name_skip(const u_char **ptrptr, const u_char *eom) cp += n; continue; case NS_TYPE_ELT: /*%< EDNS0 extended label */ - if ((l = labellen(cp - 1)) < 0) { + if (cp < eom && (l = labellen(cp - 1)) < 0) { errno = EMSGSIZE; /*%< XXX */ return (-1); }
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