From cf50871b8ef5321840cd9a7b9f3062f17b875f23 Mon Sep 17 00:00:00 2001 From: Jenny Guanni Qu Date: Thu, 12 Mar 2026 22:49:50 +0800 Subject: [PATCH] netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ANBZ: #32870 commit f173d0f4c0f689173f8cdac79991043a4a89bf66 upstream. In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement. Fixes: 5e35941d9901 ("[NETFILTER]: Add H.323 conntrack/NAT helper") Reported-by: Klaudia Kloc Reported-by: Dawid Moczadło Tested-by: Jenny Guanni Qu Signed-off-by: Jenny Guanni Qu Signed-off-by: Florian Westphal Fixes: CVE-2026-23455 Signed-off-by: PatchPilot Signed-off-by: Ferry Meng --- net/netfilter/nf_conntrack_h323_asn1.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/netfilter/nf_conntrack_h323_asn1.c b/net/netfilter/nf_conntrack_h323_asn1.c index e697a824b001..66be34457eef 100644 --- a/net/netfilter/nf_conntrack_h323_asn1.c +++ b/net/netfilter/nf_conntrack_h323_asn1.c @@ -918,6 +918,8 @@ int DecodeQ931(unsigned char *buf, size_t sz, Q931 *q931) break; p++; len--; + if (len <= 0) + break; return DecodeH323_UserInformation(buf, p, len, &q931->UUIE); } -- Gitee