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* [PATCH] USB: xhci: dbc: fix tty registration race
@ 2021-09-28 12:04 Johan Hovold
  2021-09-30  9:24 ` Mathias Nyman
  0 siblings, 1 reply; 2+ messages in thread
From: Johan Hovold @ 2021-09-28 12:04 UTC (permalink / raw)
  To: Mathias Nyman
  Cc: Greg Kroah-Hartman, linux-usb, linux-kernel, Johan Hovold,
	stable, Lu Baolu

Make sure to allocate resources before registering the tty device to
avoid having a racing open() and write() fail to enable rx or
dereference a NULL pointer when accessing the uninitialised fifo.

Fixes: dfba2174dc42 ("usb: xhci: Add DbC support in xHCI driver")
Cc: stable@vger.kernel.org      # 4.16
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/host/xhci-dbgtty.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index 6e784f2fc26d..eb46e642e87a 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -408,40 +408,38 @@ static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
 		return -EBUSY;
 
 	xhci_dbc_tty_init_port(dbc, port);
-	tty_dev = tty_port_register_device(&port->port,
-					   dbc_tty_driver, 0, NULL);
-	if (IS_ERR(tty_dev)) {
-		ret = PTR_ERR(tty_dev);
-		goto register_fail;
-	}
 
 	ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
 	if (ret)
-		goto buf_alloc_fail;
+		goto err_exit_port;
 
 	ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
 				      dbc_read_complete);
 	if (ret)
-		goto request_fail;
+		goto err_free_fifo;
 
 	ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
 				      dbc_write_complete);
 	if (ret)
-		goto request_fail;
+		goto err_free_requests;
+
+	tty_dev = tty_port_register_device(&port->port,
+					   dbc_tty_driver, 0, NULL);
+	if (IS_ERR(tty_dev)) {
+		ret = PTR_ERR(tty_dev);
+		goto err_free_requests;
+	}
 
 	port->registered = true;
 
 	return 0;
 
-request_fail:
+err_free_requests:
 	xhci_dbc_free_requests(&port->read_pool);
 	xhci_dbc_free_requests(&port->write_pool);
+err_free_fifo:
 	kfifo_free(&port->write_fifo);
-
-buf_alloc_fail:
-	tty_unregister_device(dbc_tty_driver, 0);
-
-register_fail:
+err_exit_port:
 	xhci_dbc_tty_exit_port(port);
 
 	dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
-- 
2.32.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] USB: xhci: dbc: fix tty registration race
  2021-09-28 12:04 [PATCH] USB: xhci: dbc: fix tty registration race Johan Hovold
@ 2021-09-30  9:24 ` Mathias Nyman
  0 siblings, 0 replies; 2+ messages in thread
From: Mathias Nyman @ 2021-09-30  9:24 UTC (permalink / raw)
  To: Johan Hovold, Mathias Nyman
  Cc: Greg Kroah-Hartman, linux-usb, linux-kernel, stable, Lu Baolu

On 28.9.2021 15.04, Johan Hovold wrote:
> Make sure to allocate resources before registering the tty device to
> avoid having a racing open() and write() fail to enable rx or
> dereference a NULL pointer when accessing the uninitialised fifo.
> 
> Fixes: dfba2174dc42 ("usb: xhci: Add DbC support in xHCI driver")
> Cc: stable@vger.kernel.org      # 4.16
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Thanks, adding to queue

-Mathias


^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2021-09-30  9:21 UTC | newest]

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