From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , John Fastabend , Alexei Starovoitov , Sasha Levin Subject: [PATCH 4.18 013/168] bpf, sockmap: fix psock refcount leak in bpf_tcp_recvmsg Date: Mon, 8 Oct 2018 20:29:53 +0200 Message-Id: <20181008175620.542501811@linuxfoundation.org> In-Reply-To: <20181008175620.043587728@linuxfoundation.org> References: <20181008175620.043587728@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 15c480efab01197c965ce0562a43ffedd852b8f9 ] In bpf_tcp_recvmsg() we first took a reference on the psock, however once we find that there are skbs in the normal socket's receive queue we return with processing them through tcp_recvmsg(). Problem is that we leak the taken reference on the psock in that path. Given we don't really do anything with the psock at this point, move the skb_queue_empty() test before we fetch the psock to fix this case. Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support") Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/sockmap.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -915,6 +915,8 @@ static int bpf_tcp_recvmsg(struct sock * if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); + if (!skb_queue_empty(&sk->sk_receive_queue)) + return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); rcu_read_lock(); psock = smap_psock_sk(sk); @@ -925,9 +927,6 @@ static int bpf_tcp_recvmsg(struct sock * goto out; rcu_read_unlock(); - if (!skb_queue_empty(&sk->sk_receive_queue)) - return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); - lock_sock(sk); bytes_ready: while (copied != len) {