From c2f34a65a61cd1ace3b53c93e8b38d2f79f4ff0d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 14 Oct 2015 05:58:38 -0700 Subject: [PATCH] tcp/dccp: fix potential NULL deref in __inet_inherit_port() As we no longer hold listener lock in fast path, it is possible that a child is created right after listener freed its bound port, if a close() is done while incoming packets are processed. __inet_inherit_port() must detect this and return an error, so that caller can free the child earlier. Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets") Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/inet_hashtables.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 08643a3616af..958728a22001 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -137,6 +137,10 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child) spin_lock(&head->lock); tb = inet_csk(sk)->icsk_bind_hash; + if (unlikely(!tb)) { + spin_unlock(&head->lock); + return -ENOENT; + } if (tb->port != port) { /* NOTE: using tproxy and redirecting skbs to a proxy * on a different listener port breaks the assumption -- 2.20.1