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authorEric Dumazet <edumazet@google.com>2018-10-01 23:24:26 -0700
committerDavid S. Miller <davem@davemloft.net>2018-10-02 22:17:35 -0700
commit8873c064d1de579ea23412a6d3eee972593f142b (patch)
treec7c1d16fc8403b48ff2b5f0cd8775b9f383ceea5 /net
parentnet: inet6_rtm_getroute() - use new style struct initializer instead of memset (diff)
downloadlinux-dev-8873c064d1de579ea23412a6d3eee972593f142b.tar.xz
linux-dev-8873c064d1de579ea23412a6d3eee972593f142b.zip
tcp: do not release socket ownership in tcp_close()
syzkaller was able to hit the WARN_ON(sock_owned_by_user(sk)); in tcp_close() While a socket is being closed, it is very possible other threads find it in rtnetlink dump. tcp_get_info() will acquire the socket lock for a short amount of time (slow = lock_sock_fast(sk)/unlock_sock_fast(sk, slow);), enough to trigger the warning. Fixes: 67db3e4bfbc9 ("tcp: no longer hold ehash lock while calling tcp_get_info()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/sock.c2
-rw-r--r--net/ipv4/tcp.c11
2 files changed, 4 insertions, 9 deletions
diff --git a/net/core/sock.c b/net/core/sock.c
index 8537b6ca72c5..7e8796a6a089 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2317,7 +2317,7 @@ static void __lock_sock(struct sock *sk)
finish_wait(&sk->sk_lock.wq, &wait);
}
-static void __release_sock(struct sock *sk)
+void __release_sock(struct sock *sk)
__releases(&sk->sk_lock.slock)
__acquires(&sk->sk_lock.slock)
{
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2827fa5643bd..43ef83b2330e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2416,16 +2416,10 @@ adjudge_to_death:
sock_hold(sk);
sock_orphan(sk);
- /* It is the last release_sock in its life. It will remove backlog. */
- release_sock(sk);
-
-
- /* Now socket is owned by kernel and we acquire BH lock
- * to finish close. No need to check for user refs.
- */
local_bh_disable();
bh_lock_sock(sk);
- WARN_ON(sock_owned_by_user(sk));
+ /* remove backlog if any, without releasing ownership. */
+ __release_sock(sk);
percpu_counter_inc(sk->sk_prot->orphan_count);
@@ -2494,6 +2488,7 @@ adjudge_to_death:
out:
bh_unlock_sock(sk);
local_bh_enable();
+ release_sock(sk);
sock_put(sk);
}
EXPORT_SYMBOL(tcp_close);