From: Lorenzo Bianconi lorenzo.bianconi@redhat.com
[ Upstream commit 988dc4a9a3b66be75b30405a5494faf0dc7cffb6 ]
gue tunnels run iptunnel_pull_offloads on received skbs. This can determine a possible use-after-free accessing guehdr pointer since the packet will be 'uncloned' running pskb_expand_head if it is a cloned gso skb (e.g if the packet has been sent though a veth device)
Fixes: a09a4c8dd1ec ("tunnels: Remove encapsulation offloads on decap") Signed-off-by: Lorenzo Bianconi lorenzo.bianconi@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/fou.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/ipv4/fou.c +++ b/net/ipv4/fou.c @@ -116,6 +116,7 @@ static int gue_udp_recv(struct sock *sk, struct guehdr *guehdr; void *data; u16 doffset = 0; + u8 proto_ctype;
if (!fou) return 1; @@ -173,13 +174,14 @@ static int gue_udp_recv(struct sock *sk, if (unlikely(guehdr->control)) return gue_control_message(skb, guehdr);
+ proto_ctype = guehdr->proto_ctype; __skb_pull(skb, sizeof(struct udphdr) + hdrlen); skb_reset_transport_header(skb);
if (iptunnel_pull_offloads(skb)) goto drop;
- return -guehdr->proto_ctype; + return -proto_ctype;
drop: kfree_skb(skb);