From: David Howells dhowells@redhat.com
[ Upstream commit f0308fb0708078d6c1d8a4d533941a7a191af634 ]
If an ICMP packet comes in on the UDP socket backing an AF_RXRPC socket as the UDP socket is being shut down, rxrpc_error_report() may get called to deal with it after sk_user_data on the UDP socket has been cleared, leading to a NULL pointer access when this local endpoint record gets accessed.
Fix this by just returning immediately if sk_user_data was NULL.
The oops looks like the following:
#PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... RIP: 0010:rxrpc_error_report+0x1bd/0x6a9 ... Call Trace: ? sock_queue_err_skb+0xbd/0xde ? __udp4_lib_err+0x313/0x34d __udp4_lib_err+0x313/0x34d icmp_unreach+0x1ee/0x207 icmp_rcv+0x25b/0x28f ip_protocol_deliver_rcu+0x95/0x10e ip_local_deliver+0xe9/0x148 __netif_receive_skb_one_core+0x52/0x6e process_backlog+0xdc/0x177 net_rx_action+0xf9/0x270 __do_softirq+0x1b6/0x39a ? smpboot_register_percpu_thread+0xce/0xce run_ksoftirqd+0x1d/0x42 smpboot_thread_fn+0x19e/0x1b3 kthread+0xf1/0xf6 ? kthread_delayed_work_timer_fn+0x83/0x83 ret_from_fork+0x24/0x30
Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Reported-by: syzbot+611164843bd48cc2190c@syzkaller.appspotmail.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/rxrpc/peer_event.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index dc7fdaf20445..42582a9ff81d 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -153,6 +153,9 @@ void rxrpc_error_report(struct sock *sk) struct rxrpc_peer *peer; struct sk_buff *skb;
+ if (unlikely(!local)) + return; + _enter("%p{%d}", sk, local->debug_id);
skb = sock_dequeue_err_skb(sk);