From: Zhixing Chen Date: Wed, 8 Jul 2026 04:22:44 +0000 (+0800) Subject: gtp: parse extension headers before reading inner protocol X-Git-Tag: v7.2-rc5~27^2~105 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=96e37e2f618e931aa97af95e707dcdfb1ec41264;p=thirdparty%2Flinux.git gtp: parse extension headers before reading inner protocol GTPv1-U packets may carry a chain of extension headers before the inner IP packet. The receive path already parses and skips these extension headers, but it currently reads the inner protocol before doing so. As a result, the first extension header byte is interpreted as the inner IP version. Packets with extension headers are then dropped before PDP lookup. Parse the extension header chain before calling gtp_inner_proto(), so the inner protocol is read from the actual inner IP header. Fixes: c75fc0b9e5be ("gtp: identify tunnel via GTP device + GTP version + TEID + family") Signed-off-by: Zhixing Chen Link: https://patch.msgid.link/20260708042244.120898-1-running910@gmail.com Signed-off-by: Paolo Abeni --- diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index a60ef32b35b8..c0e38878af51 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -826,13 +826,17 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb) if (!pskb_may_pull(skb, hdrlen)) return -1; + gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr)); + + if (gtp1->flags & GTP1_F_EXTHDR && + gtp_parse_exthdrs(skb, &hdrlen) < 0) + return -1; + if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) { netdev_dbg(gtp->dev, "GTP packet does not encapsulate an IP packet\n"); return -1; } - gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr)); - pctx = gtp1_pdp_find(gtp, ntohl(gtp1->tid), gtp_proto_to_family(inner_proto)); if (!pctx) { @@ -840,10 +844,6 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb) return 1; } - if (gtp1->flags & GTP1_F_EXTHDR && - gtp_parse_exthdrs(skb, &hdrlen) < 0) - return -1; - return gtp_rx(pctx, skb, hdrlen, gtp->role, inner_proto); }