From 146d8fef9da1ba854de7fa28b9cb9eb147535f88 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 4 Mar 2017 00:01:41 +0000 Subject: [PATCH] rxrpc: Call state should be read with READ_ONCE() under some circumstances The call state may be changed at any time by the data-ready routine in response to received packets, so if the call state is to be read and acted upon several times in a function, READ_ONCE() must be used unless the call state lock is held. Signed-off-by: David Howells Signed-off-by: David S. Miller --- net/rxrpc/input.c | 12 +++++++----- net/rxrpc/recvmsg.c | 4 ++-- net/rxrpc/sendmsg.c | 48 ++++++++++++++++++++++++++++----------------- 3 files changed, 39 insertions(+), 25 deletions(-) diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 9f4cfa25af7c..d74921c4969b 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -420,6 +420,7 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb, u16 skew) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + enum rxrpc_call_state state; unsigned int offset = sizeof(struct rxrpc_wire_header); unsigned int ix; rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0; @@ -434,14 +435,15 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb, _proto("Rx DATA %%%u { #%u f=%02x }", sp->hdr.serial, seq, sp->hdr.flags); - if (call->state >= RXRPC_CALL_COMPLETE) + state = READ_ONCE(call->state); + if (state >= RXRPC_CALL_COMPLETE) return; /* Received data implicitly ACKs all of the request packets we sent * when we're acting as a client. */ - if ((call->state == RXRPC_CALL_CLIENT_SEND_REQUEST || - call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) && + if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST || + state == RXRPC_CALL_CLIENT_AWAIT_REPLY) && !rxrpc_receiving_reply(call)) return; @@ -799,7 +801,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb, return rxrpc_proto_abort("AK0", call, 0); /* Ignore ACKs unless we are or have just been transmitting. */ - switch (call->state) { + switch (READ_ONCE(call->state)) { case RXRPC_CALL_CLIENT_SEND_REQUEST: case RXRPC_CALL_CLIENT_AWAIT_REPLY: case RXRPC_CALL_SERVER_SEND_REPLY: @@ -940,7 +942,7 @@ static void rxrpc_input_call_packet(struct rxrpc_call *call, static void rxrpc_input_implicit_end_call(struct rxrpc_connection *conn, struct rxrpc_call *call) { - switch (call->state) { + switch (READ_ONCE(call->state)) { case RXRPC_CALL_SERVER_AWAIT_ACK: rxrpc_call_completed(call); break; diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c index 6491ca46a03f..3e2f1a8e9c5b 100644 --- a/net/rxrpc/recvmsg.c +++ b/net/rxrpc/recvmsg.c @@ -527,7 +527,7 @@ try_again: msg->msg_namelen = len; } - switch (call->state) { + switch (READ_ONCE(call->state)) { case RXRPC_CALL_SERVER_ACCEPTING: ret = rxrpc_recvmsg_new_call(rx, call, msg, flags); break; @@ -640,7 +640,7 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call, mutex_lock(&call->user_mutex); - switch (call->state) { + switch (READ_ONCE(call->state)) { case RXRPC_CALL_CLIENT_RECV_REPLY: case RXRPC_CALL_SERVER_RECV_REQUEST: case RXRPC_CALL_SERVER_ACK_REQUEST: diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index bc2d3dcff9de..47ccfeacc1c6 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -488,6 +488,7 @@ rxrpc_new_client_call_for_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) __releases(&rx->sk.sk_lock.slock) { + enum rxrpc_call_state state; enum rxrpc_command cmd; struct rxrpc_call *call; unsigned long user_call_ID = 0; @@ -526,13 +527,17 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) return PTR_ERR(call); /* ... and we have the call lock. */ } else { - ret = -EBUSY; - if (call->state == RXRPC_CALL_UNINITIALISED || - call->state == RXRPC_CALL_CLIENT_AWAIT_CONN || - call->state == RXRPC_CALL_SERVER_PREALLOC || - call->state == RXRPC_CALL_SERVER_SECURING || - call->state == RXRPC_CALL_SERVER_ACCEPTING) + switch (READ_ONCE(call->state)) { + case RXRPC_CALL_UNINITIALISED: + case RXRPC_CALL_CLIENT_AWAIT_CONN: + case RXRPC_CALL_SERVER_PREALLOC: + case RXRPC_CALL_SERVER_SECURING: + case RXRPC_CALL_SERVER_ACCEPTING: + ret = -EBUSY; goto error_release_sock; + default: + break; + } ret = mutex_lock_interruptible(&call->user_mutex); release_sock(&rx->sk); @@ -542,10 +547,11 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) } } + state = READ_ONCE(call->state); _debug("CALL %d USR %lx ST %d on CONN %p", - call->debug_id, call->user_call_ID, call->state, call->conn); + call->debug_id, call->user_call_ID, state, call->conn); - if (call->state >= RXRPC_CALL_COMPLETE) { + if (state >= RXRPC_CALL_COMPLETE) { /* it's too late for this call */ ret = -ESHUTDOWN; } else if (cmd == RXRPC_CMD_SEND_ABORT) { @@ -555,12 +561,12 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) } else if (cmd != RXRPC_CMD_SEND_DATA) { ret = -EINVAL; } else if (rxrpc_is_client_call(call) && - call->state != RXRPC_CALL_CLIENT_SEND_REQUEST) { + state != RXRPC_CALL_CLIENT_SEND_REQUEST) { /* request phase complete for this client call */ ret = -EPROTO; } else if (rxrpc_is_service_call(call) && - call->state != RXRPC_CALL_SERVER_ACK_REQUEST && - call->state != RXRPC_CALL_SERVER_SEND_REPLY) { + state != RXRPC_CALL_SERVER_ACK_REQUEST && + state != RXRPC_CALL_SERVER_SEND_REPLY) { /* Reply phase not begun or not complete for service call. */ ret = -EPROTO; } else { @@ -605,14 +611,20 @@ int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call, _debug("CALL %d USR %lx ST %d on CONN %p", call->debug_id, call->user_call_ID, call->state, call->conn); - if (call->state >= RXRPC_CALL_COMPLETE) { - ret = -ESHUTDOWN; /* it's too late for this call */ - } else if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST && - call->state != RXRPC_CALL_SERVER_ACK_REQUEST && - call->state != RXRPC_CALL_SERVER_SEND_REPLY) { - ret = -EPROTO; /* request phase complete for this client call */ - } else { + switch (READ_ONCE(call->state)) { + case RXRPC_CALL_CLIENT_SEND_REQUEST: + case RXRPC_CALL_SERVER_ACK_REQUEST: + case RXRPC_CALL_SERVER_SEND_REPLY: ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len); + break; + case RXRPC_CALL_COMPLETE: + /* It's too late for this call */ + ret = -ESHUTDOWN; + break; + default: + /* Request phase complete for this client call */ + ret = -EPROTO; + break; } mutex_unlock(&call->user_mutex);