From: John Fastabend john.fastabend@gmail.com
commit 4da6a196f93b1af7612340e8c1ad8ce71e18f955 upstream.
When a sockmap is free'd and a socket in the map is enabled with tls we tear down the bpf context on the socket, the psock struct and state, and then call tcp_update_ulp(). The tcp_update_ulp() call is to inform the tls stack it needs to update its saved sock ops so that when the tls socket is later destroyed it doesn't try to call the now destroyed psock hooks.
This is about keeping stacked ULPs in good shape so they always have the right set of stacked ops.
However, recently unhash() hook was removed from TLS side. But, the sockmap/bpf side is not doing any extra work to update the unhash op when is torn down instead expecting TLS side to manage it. So both TLS and sockmap believe the other side is managing the op and instead no one updates the hook so it continues to point at tcp_bpf_unhash(). When unhash hook is called we call tcp_bpf_unhash() which detects the psock has already been destroyed and calls sk->sk_prot_unhash() which calls tcp_bpf_unhash() yet again and so on looping and hanging the core.
To fix have sockmap tear down logic fixup the stale pointer.
Fixes: 5d92e631b8be ("net/tls: partially revert fix transition through disconnect with close") Reported-by: syzbot+83979935eb6304f8cd46@syzkaller.appspotmail.com Signed-off-by: John Fastabend john.fastabend@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Jakub Sitnicki jakub@cloudflare.com Acked-by: Song Liu songliubraving@fb.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20200111061206.8028-2-john.fastabend@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/skmsg.h | 1 + 1 file changed, 1 insertion(+)
--- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -354,6 +354,7 @@ static inline void sk_psock_update_proto static inline void sk_psock_restore_proto(struct sock *sk, struct sk_psock *psock) { + sk->sk_prot->unhash = psock->saved_unhash; sk->sk_write_space = psock->saved_write_space;
if (psock->sk_proto) {