This is a note to let you know that I've just added the patch titled net, sk_msg: Don't check if sock is locked when tearing down psock to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-sk_msg-don-t-check-if-sock-is-locked-when-tearing-down-psock.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 58c8db929db1c1d785a6f5d8f8692e5dbcc35e84 Mon Sep 17 00:00:00 2001 From: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> Date: Tue, 21 Jan 2020 13:31:47 +0100 Subject: net, sk_msg: Don't check if sock is locked when tearing down psock From: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx Suggested-by: John Fastabend <john.fastabend@xxxxxxxxx> Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx> Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/core/skmsg.c | 2 -- 1 file changed, 2 deletions(-) --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -594,8 +594,6 @@ EXPORT_SYMBOL_GPL(sk_psock_destroy); void sk_psock_drop(struct sock *sk, struct sk_psock *psock) { - sock_owned_by_me(sk); - sk_psock_cork_free(psock); sk_psock_zap_ingress(psock); Patches currently in stable-queue which might be from jakub@xxxxxxxxxxxxxx are queue-5.4/net-sk_msg-don-t-check-if-sock-is-locked-when-tearing-down-psock.patch