rxrpc: Fix timeout of a call that hasn't yet been granted a channel

afs_make_call() calls rxrpc_kernel_begin_call() to begin a call (which may
get stalled in the background waiting for a connection to become
available); it then calls rxrpc_kernel_set_max_life() to set the timeouts -
but that starts the call timer so the call timer might then expire before
we get a connection assigned - leading to the following oops if the call
stalled:

	BUG: kernel NULL pointer dereference, address: 0000000000000000
	...
	CPU: 1 PID: 5111 Comm: krxrpcio/0 Not tainted 6.3.0-rc7-build3+ #701
	RIP: 0010:rxrpc_alloc_txbuf+0xc0/0x157
	...
	Call Trace:
	 <TASK>
	 rxrpc_send_ACK+0x50/0x13b
	 rxrpc_input_call_event+0x16a/0x67d
	 rxrpc_io_thread+0x1b6/0x45f
	 ? _raw_spin_unlock_irqrestore+0x1f/0x35
	 ? rxrpc_input_packet+0x519/0x519
	 kthread+0xe7/0xef
	 ? kthread_complete_and_exit+0x1b/0x1b
	 ret_from_fork+0x22/0x30

Fix this by noting the timeouts in struct rxrpc_call when the call is
created.  The timer will be started when the first packet is transmitted.

It shouldn't be possible to trigger this directly from userspace through
AF_RXRPC as sendmsg() will return EBUSY if the call is in the
waiting-for-conn state if it dropped out of the wait due to a signal.

Fixes: 9d35d880e0e4 ("rxrpc: Move client call connection to the I/O thread")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
cc: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 13 insertions, 1 deletions

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index c32b164206f9..31f738d65f1c 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -265,6 +265,7 @@ static int rxrpc_listen(struct socket *sock, int backlog)
  * @key: The security context to use (defaults to socket setting)
  * @user_call_ID: The ID to use
  * @tx_total_len: Total length of data to transmit during the call (or -1)
+ * @hard_timeout: The maximum lifespan of the call in sec
  * @gfp: The allocation constraints
  * @notify_rx: Where to send notifications instead of socket queue
  * @upgrade: Request service upgrade for call
@@ -283,6 +284,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 					   struct key *key,
 					   unsigned long user_call_ID,
 					   s64 tx_total_len,
+					   u32 hard_timeout,
 					   gfp_t gfp,
 					   rxrpc_notify_rx_t notify_rx,
 					   bool upgrade,
@@ -313,6 +315,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 	p.tx_total_len		= tx_total_len;
 	p.interruptibility	= interruptibility;
 	p.kernel		= true;
+	p.timeouts.hard		= hard_timeout;
 
 	memset(&cp, 0, sizeof(cp));
 	cp.local		= rx->local;
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 67b0a894162d..5d44dc08f66d 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -616,6 +616,7 @@ struct rxrpc_call {
 	unsigned long		expect_term_by;	/* When we expect call termination by */
 	u32			next_rx_timo;	/* Timeout for next Rx packet (jif) */
 	u32			next_req_timo;	/* Timeout for next Rx request packet (jif) */
+	u32			hard_timo;	/* Maximum lifetime or 0 (jif) */
 	struct timer_list	timer;		/* Combined event timer */
 	struct work_struct	destroyer;	/* In-process-context destroyer */
 	rxrpc_notify_rx_t	notify_rx;	/* kernel service Rx notification function */
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index e9f1f49d18c2..fecbc73054bc 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -226,6 +226,13 @@ static struct rxrpc_call *rxrpc_alloc_client_call(struct rxrpc_sock *rx,
 	if (cp->exclusive)
 		__set_bit(RXRPC_CALL_EXCLUSIVE, &call->flags);
 
+	if (p->timeouts.normal)
+		call->next_rx_timo = min(msecs_to_jiffies(p->timeouts.normal), 1UL);
+	if (p->timeouts.idle)
+		call->next_req_timo = min(msecs_to_jiffies(p->timeouts.idle), 1UL);
+	if (p->timeouts.hard)
+		call->hard_timo = p->timeouts.hard * HZ;
+
 	ret = rxrpc_init_client_call_security(call);
 	if (ret < 0) {
 		rxrpc_prefail_call(call, RXRPC_CALL_LOCAL_ERROR, ret);
@@ -257,7 +264,7 @@ void rxrpc_start_call_timer(struct rxrpc_call *call)
 	call->keepalive_at = j;
 	call->expect_rx_by = j;
 	call->expect_req_by = j;
-	call->expect_term_by = j;
+	call->expect_term_by = j + call->hard_timo;
 	call->timer.expires = now;
 }
 
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index c1b074c17b33..8e0b94714e84 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -651,6 +651,7 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
 		if (IS_ERR(call))
 			return PTR_ERR(call);
 		/* ... and we have the call lock. */
+		p.call.nr_timeouts = 0;
 		ret = 0;
 		if (rxrpc_call_is_complete(call))
 			goto out_put_unlock;