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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: ace45bec6d ("rxrpc: Fix firewall route keepalive")
Fixes: 2baec2c3f8 ("rxrpc: Support network namespacing")
Reported-by: syzbot+b9be979c55f2bea8ed30@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2019-10-07 10:58:29 +01:00
parent 48c9e0ec7c
commit 9ebeddef58
1 changed files with 3 additions and 2 deletions
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5
net/rxrpc/peer_object.c
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@ -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);
}
}