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rxrpc: use rcu protection while reading sk->sk_user_data

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We need to extend the rcu_read_lock() section in rxrpc_error_report()
and use rcu_dereference_sk_user_data() instead of plain access
to sk->sk_user_data to make sure all rules are respected.

The compiler wont reload sk->sk_user_data at will, and RCU rules
prevent memory beeing freed too soon.

Fixes: f0308fb070 ("rxrpc: Fix possible NULL pointer access in ICMP handling")
Fixes: 17926a7932 ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2019-10-14 06:04:38 -07:00 committed by David S. Miller
parent bd74708cd9
commit 2ca4f6ca45
1 changed files with 8 additions and 4 deletions
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12
net/rxrpc/peer_event.c
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@ -147,13 +147,16 @@ void rxrpc_error_report(struct sock *sk)
{
struct sock_exterr_skb *serr;
struct sockaddr_rxrpc srx;
struct rxrpc_local *local = sk->sk_user_data;
struct rxrpc_local *local;
struct rxrpc_peer *peer;
struct sk_buff *skb;
if (unlikely(!local))
rcu_read_lock();
local = rcu_dereference_sk_user_data(sk);
if (unlikely(!local)) {
rcu_read_unlock();
return;
}
_enter("%p{%d}", sk, local->debug_id);
/* Clear the outstanding error value on the socket so that it doesn't
@ -163,6 +166,7 @@ void rxrpc_error_report(struct sock *sk)
skb = sock_dequeue_err_skb(sk);
if (!skb) {
rcu_read_unlock();
_leave("UDP socket errqueue empty");
return;
}
@ -170,11 +174,11 @@ void rxrpc_error_report(struct sock *sk)
serr = SKB_EXT_ERR(skb);
if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) {
_leave("UDP empty message");
rcu_read_unlock();
rxrpc_free_skb(skb, rxrpc_skb_freed);
return;
}
rcu_read_lock();
peer = rxrpc_lookup_peer_icmp_rcu(local, skb, &srx);
if (peer && !rxrpc_get_peer_maybe(peer))
peer = NULL;