Date: Fri, 1 Mar 2019 07:37:46 +0000 (UTC) From: Kristof Provost <kp@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r344691 - head/sys/netpfil/pf Message-ID: <201903010737.x217bk6v028785@repo.freebsd.org>
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Author: kp Date: Fri Mar 1 07:37:45 2019 New Revision: 344691 URL: https://svnweb.freebsd.org/changeset/base/344691 Log: pf: IPv6 fragments with malformed extension headers could be erroneously passed by pf or cause a panic We mistakenly used the extoff value from the last packet to patch the next_header field. If a malicious host sends a chain of fragmented packets where the first packet and the final packet have different lengths or number of extension headers we'd patch the next_header at the wrong offset. This can potentially lead to panics or rule bypasses. Security: CVE-2019-5597 Obtained from: OpenBSD Reported by: Corentin Bayet, Nicolas Collignon, Luca Moro at Synacktiv Modified: head/sys/netpfil/pf/pf_norm.c Modified: head/sys/netpfil/pf/pf_norm.c ============================================================================== --- head/sys/netpfil/pf/pf_norm.c Fri Mar 1 05:54:13 2019 (r344690) +++ head/sys/netpfil/pf/pf_norm.c Fri Mar 1 07:37:45 2019 (r344691) @@ -836,11 +836,11 @@ pf_reassemble6(struct mbuf **m0, struct ip6_hdr *ip6, } /* We have all the data. */ + frent = TAILQ_FIRST(&frag->fr_queue); + KASSERT(frent != NULL, ("frent != NULL")); extoff = frent->fe_extoff; maxlen = frag->fr_maxlen; frag_id = frag->fr_id; - frent = TAILQ_FIRST(&frag->fr_queue); - KASSERT(frent != NULL, ("frent != NULL")); total = TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_off + TAILQ_LAST(&frag->fr_queue, pf_fragq)->fe_len; hdrlen = frent->fe_hdrlen - sizeof(struct ip6_frag);
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