diff options
| author | Eric Dumazet <edumazet@google.com> | 2018-10-02 09:24:26 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-10-03 08:17:35 +0300 |
| commit | 8873c064d1de579ea23412a6d3eee972593f142b (patch) | |
| tree | c7c1d16fc8403b48ff2b5f0cd8775b9f383ceea5 | |
| parent | 744486d426dce4e4dc25fd2ce750116a0025736c (diff) | |
| download | linux-8873c064d1de579ea23412a6d3eee972593f142b.tar.xz | |
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>
| -rw-r--r-- | include/net/sock.h | 1 | ||||
| -rw-r--r-- | net/core/sock.c | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 11 |
3 files changed, 5 insertions, 9 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 38cae35f6e16..751549ac0a84 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1492,6 +1492,7 @@ static inline void lock_sock(struct sock *sk) lock_sock_nested(sk, 0); } +void __release_sock(struct sock *sk); void release_sock(struct sock *sk); /* BH context may only use the following locking interface. */ 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); |