| From 53d5cd627cac07b127c886b73d73be6aa865b3bc Mon Sep 17 00:00:00 2001 |
| From: Jakub Sitnicki <jakub@cloudflare.com> |
| Date: Tue, 21 Jan 2020 13:31:47 +0100 |
| Subject: [PATCH] net, sk_msg: Don't check if sock is locked when tearing down |
| psock |
| |
| commit 58c8db929db1c1d785a6f5d8f8692e5dbcc35e84 upstream. |
| |
| As John Fastabend reports [0], psock state tear-down can happen on receive |
| path *after* unlocking the socket, if the only other psock user, that is |
| sockmap or sockhash, releases its psock reference before tcp_bpf_recvmsg |
| does so: |
| |
| tcp_bpf_recvmsg() |
| psock = sk_psock_get(sk) <- refcnt 2 |
| lock_sock(sk); |
| ... |
| sock_map_free() <- refcnt 1 |
| release_sock(sk) |
| sk_psock_put() <- refcnt 0 |
| |
| Remove the lockdep check for socket lock in psock tear-down that got |
| introduced in 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during |
| tear down"). |
| |
| [0] https://lore.kernel.org/netdev/5e25dc995d7d_74082aaee6e465b441@john-XPS-13-9370.notmuch/ |
| |
| Fixes: 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during tear down") |
| Reported-by: syzbot+d73682fcf7fee6982fe3@syzkaller.appspotmail.com |
| Suggested-by: John Fastabend <john.fastabend@gmail.com> |
| Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> |
| Acked-by: John Fastabend <john.fastabend@gmail.com> |
| Acked-by: Daniel Borkmann <daniel@iogearbox.net> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/net/core/skmsg.c b/net/core/skmsg.c |
| index 5b754427688c..fc6f99dcddfd 100644 |
| --- a/net/core/skmsg.c |
| +++ b/net/core/skmsg.c |
| @@ -596,8 +596,6 @@ EXPORT_SYMBOL_GPL(sk_psock_destroy); |
| void sk_psock_drop(struct sock *sk, struct sk_psock *psock) |
| { |
| rcu_assign_sk_user_data(sk, NULL); |
| - sock_owned_by_me(sk); |
| - |
| sk_psock_cork_free(psock); |
| sk_psock_zap_ingress(psock); |
| sk_psock_restore_proto(sk, psock); |
| -- |
| 2.7.4 |
| |
