| Message ID | 157071915431.29197.5055122258964729288.stgit@warthog.procyon.org.uk |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] rxrpc: Fix possible NULL pointer access in ICMP handling | expand |
From: David Howells <dhowells@redhat.com> Date: Thu, 10 Oct 2019 15:52:34 +0100 > 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: ... > 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> Applied and queued up for -stable, thanks.
On 10/10/19 7:52 AM, David Howells wrote: > 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> > --- > > 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 c97ebdc043e4..61451281d74a 100644 > --- a/net/rxrpc/peer_event.c > +++ b/net/rxrpc/peer_event.c > @@ -151,6 +151,9 @@ 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); > > /* Clear the outstanding error value on the socket so that it doesn't > Okay, but we also need this. diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index c97ebdc043e44525eaecdd54bc447c1895bdca74..38db10e61f7a5cb50f9ee036b5e16ec284e723ac 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -145,9 +145,9 @@ static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, struct sock_exterr_skb *se */ void rxrpc_error_report(struct sock *sk) { + struct rxrpc_local *local = rcu_dereference_sk_user_data(sk); struct sock_exterr_skb *serr; struct sockaddr_rxrpc srx; - struct rxrpc_local *local = sk->sk_user_data; struct rxrpc_peer *peer; struct sk_buff *skb;
On 10/12/19 3:49 AM, Eric Dumazet wrote: > > Okay, but we also need this. > > diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c > index c97ebdc043e44525eaecdd54bc447c1895bdca74..38db10e61f7a5cb50f9ee036b5e16ec284e723ac 100644 > --- a/net/rxrpc/peer_event.c > +++ b/net/rxrpc/peer_event.c > @@ -145,9 +145,9 @@ static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, struct sock_exterr_skb *se > */ > void rxrpc_error_report(struct sock *sk) > { > + struct rxrpc_local *local = rcu_dereference_sk_user_data(sk); > struct sock_exterr_skb *serr; > struct sockaddr_rxrpc srx; > - struct rxrpc_local *local = sk->sk_user_data; > struct rxrpc_peer *peer; > struct sk_buff *skb; > I will psubmit the patch later once David pushes his net tree, since I do not know yet the sha1 of your patch (to provide a proper Fixes: tag)
Eric Dumazet <eric.dumazet@gmail.com> wrote: > void rxrpc_error_report(struct sock *sk) > { > + struct rxrpc_local *local = rcu_dereference_sk_user_data(sk); Acked-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index c97ebdc043e4..61451281d74a 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -151,6 +151,9 @@ 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); /* Clear the outstanding error value on the socket so that it doesn't
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> --- net/rxrpc/peer_event.c | 3 +++ 1 file changed, 3 insertions(+)