rxrpc: Fix potential call vs socket/net destruction race
rxrpc_call structs don't pin sockets or network namespaces, but may attempt
to access both after their refcount reaches 0 so that they can detach
themselves from the network namespace. However, there's no guarantee that
the socket still exists at this point (so sock_net(&call->socket->sk) may
be invalid) and the namespace may have gone away if the call isn't pinning
a peer.
Fix this by (a) carrying a net pointer in the rxrpc_call struct and (b)
waiting for all calls to be destroyed when the network namespace goes away.
This was detected by checker:
net/rxrpc/call_object.c:634:57: warning: incorrect type in argument 1 (different address spaces)
net/rxrpc/call_object.c:634:57: expected struct sock const *sk
net/rxrpc/call_object.c:634:57: got struct sock [noderef] <asn:4>*<noident>
Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing")
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 8a348e0..2a2b0fd 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -75,6 +75,7 @@ struct rxrpc_net {
u32 epoch; /* Local epoch for detecting local-end reset */
struct list_head calls; /* List of calls active in this namespace */
rwlock_t call_lock; /* Lock for ->calls */
+ atomic_t nr_calls; /* Count of allocated calls */
struct list_head conn_proc_list; /* List of conns in this namespace for proc */
struct list_head service_conns; /* Service conns in this namespace */
@@ -528,6 +529,7 @@ struct rxrpc_call {
struct rxrpc_connection *conn; /* connection carrying call */
struct rxrpc_peer *peer; /* Peer record for remote address */
struct rxrpc_sock __rcu *socket; /* socket responsible */
+ struct rxrpc_net *rxnet; /* Network namespace to which call belongs */
struct mutex user_mutex; /* User access mutex */
unsigned long ack_at; /* When deferred ACK needs to happen */
unsigned long ack_lost_at; /* When ACK is figured as lost */