From: Cong Wang <cong.wang@bytedance.com> [ Upstream commit 085c7c4e1c0e50d90b7d90f61a12e12b317a91e2 ] Both version 0 and version 1 use ETH_P_ERSPAN, but version 0 does not have an erspan header. So the check in gre_parse_header() is wrong, we have to distinguish version 1 from version 0. We can just check the gre header length like is_erspan_type1(). Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup") Reported-by: syzbot+f583ce3d4ddf9836b27a@syzkaller.appspotmail.com Cc: William Tu <u9012063@gmail.com> Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/gre_demux.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c index ad9ea82daeb3..9376b30cf626 100644 --- a/net/ipv4/gre_demux.c +++ b/net/ipv4/gre_demux.c @@ -133,7 +133,7 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, * to 0 and sets the configured key in the * inner erspan header field */ - if (greh->protocol == htons(ETH_P_ERSPAN) || + if ((greh->protocol == htons(ETH_P_ERSPAN) && hdr_len != 4) || greh->protocol == htons(ETH_P_ERSPAN2)) { struct erspan_base_hdr *ershdr; -- 2.25.1