Re: [PATCH net v2] gtp: parse extension headers before reading inner protocol

On Fri, Jul 03, 2026 at 05:37:08PM +0800, Zhixing Chen wrote:

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 running910@gmail.com

Reviewed-by: Pablo Neira Ayuso pablo@netfilter.org