From: Ignat Korchagin <ignat@xxxxxxxxxxxxxx> [ Upstream commit 46f2a11cb82b657fd15bab1c47821b635e03838b ] After sock_init_data() the allocated sk object is attached to the provided sock object. On error, packet_create() frees the sk object leaving the dangling pointer in the sock object on return. Some other code may try to use this pointer and cause use-after-free. Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx> Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Link: https://patch.msgid.link/20241014153808.51894-2-ignat@xxxxxxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/packet/af_packet.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c9c813f731c6e..9da9e41899c65 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3418,18 +3418,18 @@ static int packet_create(struct net *net, struct socket *sock, int protocol, if (sock->type == SOCK_PACKET) sock->ops = &packet_ops_spkt; + po = pkt_sk(sk); + err = packet_alloc_pending(po); + if (err) + goto out_sk_free; + sock_init_data(sock, sk); - po = pkt_sk(sk); init_completion(&po->skb_completion); sk->sk_family = PF_PACKET; po->num = proto; po->xmit = dev_queue_xmit; - err = packet_alloc_pending(po); - if (err) - goto out2; - packet_cached_dev_reset(po); sk->sk_destruct = packet_sock_destruct; @@ -3462,7 +3462,7 @@ static int packet_create(struct net *net, struct socket *sock, int protocol, sock_prot_inuse_add(net, &packet_proto, 1); return 0; -out2: +out_sk_free: sk_free(sk); out: return err; -- 2.43.0
