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 11:37:28 +0300 |
| commit | cddcc9959a32999ce2d38018900595a5ab453eb2 (patch) | |
| tree | 9b32d515c35c86a1d78d460eb5006d675a927dd8 /net | |
| parent | 5999609a93a4eb4956b6548159ce69295b1557b2 (diff) | |
| download | linux-cddcc9959a32999ce2d38018900595a5ab453eb2.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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock.c | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 11 |
2 files changed, 4 insertions, 9 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 3730eb855095..748765e35423 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 bbd07736fb0f..a32a0f4cc138 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2403,16 +2403,10 @@ 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); @@ -2481,6 +2475,7 @@ adjudge_to_death: out: bh_unlock_sock(sk); local_bh_enable(); + release_sock(sk); sock_put(sk); } EXPORT_SYMBOL(tcp_close); |