From 1dc7b90f7cd050ef6d5e511e652347e52874469c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 21 Jan 2015 03:45:42 -0800 Subject: [PATCH] ipv6: tcp: fix race in IPV6_2292PKTOPTIONS IPv6 TCP sockets store in np->pktoptions skbs, and use skb_set_owner_r() to charge the skb to socket. It means that destructor must be called while socket is locked. Therefore, we cannot use skb_get() or atomic_inc(&skb->users) to protect ourselves : kfree_skb() might race with other users manipulating sk->sk_forward_alloc Fix this race by holding socket lock for the duration of ip6_datagram_recv_ctl() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv6/ipv6_sockglue.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 66980d8d98d1..8d766d9100cb 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -996,13 +996,9 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname, lock_sock(sk); skb = np->pktoptions; if (skb) - atomic_inc(&skb->users); - release_sock(sk); - - if (skb) { ip6_datagram_recv_ctl(sk, &msg, skb); - kfree_skb(skb); - } else { + release_sock(sk); + if (!skb) { if (np->rxopt.bits.rxinfo) { struct in6_pktinfo src_info; src_info.ipi6_ifindex = np->mcast_oif ? np->mcast_oif :