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Commit 9ebeddef authored by David Howells's avatar David Howells
Browse files

rxrpc: rxrpc_peer needs to hold a ref on the rxrpc_local record 



The rxrpc_peer record needs to hold a reference on the rxrpc_local record
it points as the peer is used as a base to access information in the
rxrpc_local record.

This can cause problems in __rxrpc_put_peer(), where we need the network
namespace pointer, and in rxrpc_send_keepalive(), where we need to access
the UDP socket, leading to symptoms like:

    BUG: KASAN: use-after-free in __rxrpc_put_peer net/rxrpc/peer_object.c:411
    [inline]
    BUG: KASAN: use-after-free in rxrpc_put_peer+0x685/0x6a0
    net/rxrpc/peer_object.c:435
    Read of size 8 at addr ffff888097ec0058 by task syz-executor823/24216

Fix this by taking a ref on the local record for the peer record.

Fixes: ace45bec ("rxrpc: Fix firewall route keepalive")
Fixes: 2baec2c3 ("rxrpc: Support network namespacing")
Reported-by: default avatar <syzbot+b9be979c55f2bea8ed30@syzkaller.appspotmail.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 48c9e0ec

net/rxrpc/peer_object.c

+3 −2
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp) 
	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);

	if (peer) {

		atomic_set(&peer->usage, 1);

		peer->local = local;

		peer->local = rxrpc_get_local(local);

		INIT_HLIST_HEAD(&peer->error_targets);

		peer->service_conns = RB_ROOT;

		seqlock_init(&peer->service_conn_lock);
@@ -307,7 +307,6 @@ void rxrpc_new_incoming_peer(struct rxrpc_sock *rx, struct rxrpc_local *local, 
	unsigned long hash_key;



	hash_key = rxrpc_peer_hash_key(local, &peer->srx);

	peer->local = local;

	rxrpc_init_peer(rx, peer, hash_key);



	spin_lock(&rxnet->peer_hash_lock);
@@ -417,6 +416,7 @@ static void __rxrpc_put_peer(struct rxrpc_peer *peer) 
	list_del_init(&peer->keepalive_link);

	spin_unlock_bh(&rxnet->peer_hash_lock);



	rxrpc_put_local(peer->local);

	kfree_rcu(peer, rcu);

}
@@ -453,6 +453,7 @@ void rxrpc_put_peer_locked(struct rxrpc_peer *peer) 
	if (n == 0) {

		hash_del_rcu(&peer->hash_link);

		list_del_init(&peer->keepalive_link);

		rxrpc_put_local(peer->local);

		kfree_rcu(peer, rcu);

	}

}