| Message ID | 20190529002257.4100-2-ioanna-maria.alifieraki@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [SRU,Bionic,Cosmic,1/1] tcp: do not release socket ownership in tcp_close() | expand |
On 5/28/19 5:22 PM, Ioanna Alifieraki wrote: > From: Eric Dumazet <edumazet@google.com> > > BugLink: https://bugs.launchpad.net/bugs/1830813 > > 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> > (cherry picked from commit 8873c064d1de579ea23412a6d3eee972593f142b) > Signed-off-by: Ioanna Alifieraki <ioanna-maria.alifieraki@canonical.com> Acked-by: Connor Kuehl <connor.kuehl@canonical.com> > --- > include/net/sock.h | 1 + > net/core/sock.c | 2 +- > 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 7a7b14e9628a..5fcdd5b7b47c 100644 > --- a/include/net/sock.h > +++ b/include/net/sock.h > @@ -1461,6 +1461,7 @@ 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 1039cb1fdcff..050dba776f75 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 ba6255d934a4..8a9ea72c82fa 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -2242,16 +2242,10 @@ void tcp_close(struct sock *sk, long timeout) > 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); > > @@ -2320,6 +2314,7 @@ void tcp_close(struct sock *sk, long timeout) > out: > bh_unlock_sock(sk); > local_bh_enable(); > + release_sock(sk); > sock_put(sk); > } > EXPORT_SYMBOL(tcp_close); >
diff --git a/include/net/sock.h b/include/net/sock.h index 7a7b14e9628a..5fcdd5b7b47c 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1461,6 +1461,7 @@ 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 1039cb1fdcff..050dba776f75 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 ba6255d934a4..8a9ea72c82fa 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2242,16 +2242,10 @@ void tcp_close(struct sock *sk, long timeout) 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); @@ -2320,6 +2314,7 @@ void tcp_close(struct sock *sk, long timeout) out: bh_unlock_sock(sk); local_bh_enable(); + release_sock(sk); sock_put(sk); } EXPORT_SYMBOL(tcp_close);