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> --- 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 a705ec214254..97774bd4b6cb 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3421,17 +3421,17 @@ 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; - err = packet_alloc_pending(po); - if (err) - goto out2; - packet_cached_dev_reset(po); sk->sk_destruct = packet_sock_destruct; @@ -3463,7 +3463,7 @@ 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; -- 2.39.5
