From 3740a6078d9daefc8ce90f8e50a3cc2115908ba8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 30 Jan 2020 21:50:36 +0000 Subject: [PATCH] rxrpc: Fix NULL pointer deref due to call->conn being cleared on disconnect [ Upstream commit 5273a191dca65a675dc0bcf3909e59c6933e2831 ] When a call is disconnected, the connection pointer from the call is cleared to make sure it isn't used again and to prevent further attempted transmission for the call. Unfortunately, there might be a daemon trying to use it at the same time to transmit a packet. Fix this by keeping call->conn set, but setting a flag on the call to indicate disconnection instead. Remove also the bits in the transmission functions where the conn pointer is checked and a ref taken under spinlock as this is now redundant. Fixes: 8d94aa381dab ("rxrpc: Calls shouldn't hold socket refs") Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman --- net/rxrpc/ar-internal.h | 1 + net/rxrpc/call_object.c | 4 ++-- net/rxrpc/conn_client.c | 3 +-- net/rxrpc/conn_object.c | 4 ++-- net/rxrpc/output.c | 26 +++++++++----------------- 5 files changed, 15 insertions(+), 23 deletions(-) diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 71c7f1dd4599..b5581b0b9480 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -451,6 +451,7 @@ enum rxrpc_call_flag { RXRPC_CALL_SEND_PING, /* A ping will need to be sent */ RXRPC_CALL_PINGING, /* Ping in process */ RXRPC_CALL_RETRANS_TIMEOUT, /* Retransmission due to timeout occurred */ + RXRPC_CALL_DISCONNECTED, /* The call has been disconnected */ }; /* diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c index ddaa471a2607..7021725fa38a 100644 --- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -505,7 +505,7 @@ void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call) _debug("RELEASE CALL %p (%d CONN %p)", call, call->debug_id, conn); - if (conn) + if (conn && !test_bit(RXRPC_CALL_DISCONNECTED, &call->flags)) rxrpc_disconnect_call(call); for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++) { @@ -639,6 +639,7 @@ static void rxrpc_rcu_destroy_call(struct rcu_head *rcu) { struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu); + rxrpc_put_connection(call->conn); rxrpc_put_peer(call->peer); kfree(call->rxtx_buffer); kfree(call->rxtx_annotations); @@ -660,7 +661,6 @@ void rxrpc_cleanup_call(struct rxrpc_call *call) ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE); ASSERT(test_bit(RXRPC_CALL_RELEASED, &call->flags)); - ASSERTCMP(call->conn, ==, NULL); /* Clean up the Rx/Tx buffer */ for (i = 0; i < RXRPC_RXTX_BUFF_SIZE; i++) diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c index 0aa4bf09fb9c..05d17ec63635 100644 --- a/net/rxrpc/conn_client.c +++ b/net/rxrpc/conn_client.c @@ -762,9 +762,9 @@ void rxrpc_disconnect_client_call(struct rxrpc_call *call) struct rxrpc_net *rxnet = rxrpc_net(sock_net(&call->socket->sk)); trace_rxrpc_client(conn, channel, rxrpc_client_chan_disconnect); - call->conn = NULL; spin_lock(&conn->channel_lock); + set_bit(RXRPC_CALL_DISCONNECTED, &call->flags); /* Calls that have never actually been assigned a channel can simply be * discarded. If the conn didn't get used either, it will follow @@ -863,7 +863,6 @@ out: spin_unlock(&rxnet->client_conn_cache_lock); out_2: spin_unlock(&conn->channel_lock); - rxrpc_put_connection(conn); _leave(""); return; diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c index a48c817b792b..13b29e491de9 100644 --- a/net/rxrpc/conn_object.c +++ b/net/rxrpc/conn_object.c @@ -163,6 +163,8 @@ void __rxrpc_disconnect_call(struct rxrpc_connection *conn, _enter("%d,%x", conn->debug_id, call->cid); + set_bit(RXRPC_CALL_DISCONNECTED, &call->flags); + if (rcu_access_pointer(chan->call) == call) { /* Save the result of the call so that we can repeat it if necessary * through the channel, whilst disposing of the actual call record. @@ -207,9 +209,7 @@ void rxrpc_disconnect_call(struct rxrpc_call *call) __rxrpc_disconnect_call(conn, call); spin_unlock(&conn->channel_lock); - call->conn = NULL; conn->idle_timestamp = jiffies; - rxrpc_put_connection(conn); } /* diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index edddbacf33bc..9619c56ef4cd 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -96,7 +96,7 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_call *call, */ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping) { - struct rxrpc_connection *conn = NULL; + struct rxrpc_connection *conn; struct rxrpc_ack_buffer *pkt; struct msghdr msg; struct kvec iov[2]; @@ -106,18 +106,14 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping) int ret; u8 reason; - spin_lock_bh(&call->lock); - if (call->conn) - conn = rxrpc_get_connection_maybe(call->conn); - spin_unlock_bh(&call->lock); - if (!conn) + if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags)) return -ECONNRESET; pkt = kzalloc(sizeof(*pkt), GFP_KERNEL); - if (!pkt) { - rxrpc_put_connection(conn); + if (!pkt) return -ENOMEM; - } + + conn = call->conn; msg.msg_name = &call->peer->srx.transport; msg.msg_namelen = call->peer->srx.transport_len; @@ -204,7 +200,6 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping) } out: - rxrpc_put_connection(conn); kfree(pkt); return ret; } @@ -214,20 +209,18 @@ out: */ int rxrpc_send_abort_packet(struct rxrpc_call *call) { - struct rxrpc_connection *conn = NULL; + struct rxrpc_connection *conn; struct rxrpc_abort_buffer pkt; struct msghdr msg; struct kvec iov[1]; rxrpc_serial_t serial; int ret; - spin_lock_bh(&call->lock); - if (call->conn) - conn = rxrpc_get_connection_maybe(call->conn); - spin_unlock_bh(&call->lock); - if (!conn) + if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags)) return -ECONNRESET; + conn = call->conn; + msg.msg_name = &call->peer->srx.transport; msg.msg_namelen = call->peer->srx.transport_len; msg.msg_control = NULL; @@ -255,7 +248,6 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call) ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 1, sizeof(pkt)); - rxrpc_put_connection(conn); return ret; }