diff options
| author | Eric Dumazet <edumazet@google.com> | 2018-10-02 09:24:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-01 11:42:51 +0300 |
| commit | e6ddc2c3d89c8ed3266d83254a0c11798f33502e (patch) | |
| tree | 098611650435f0f38080ad1fc80c5ed37cf4dced | |
| parent | 6b43a9978a6b000cf05d19f8765eba0434817f94 (diff) | |
| download | linux-e6ddc2c3d89c8ed3266d83254a0c11798f33502e.tar.xz | |
tcp: do not release socket ownership in tcp_close()
commit 8873c064d1de579ea23412a6d3eee972593f142b upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 9bd5d68076d9..64a330544dad 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1452,6 +1452,7 @@ 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 68d08ed5521e..36f19458e2fe 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2242,7 +2242,7 @@ 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 f9c985460faa..8109985e78a1 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2217,16 +2217,10 @@ 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); @@ -2295,6 +2289,7 @@ adjudge_to_death: out: bh_unlock_sock(sk); local_bh_enable(); + release_sock(sk); sock_put(sk); } EXPORT_SYMBOL(tcp_close); |