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Subject[PATCH net] net: hso: fix NULL-deref on tty registration failure
Date
If resource allocation and registration fail for a muxed tty device
(e.g. if there are no more minor numbers) the driver should not try to
deregister the never-registered tty.

Fix up the error handling to avoid dereferencing a NULL pointer when
attempting to remove the character device:

BUG: kernel NULL pointer dereference, address: 0000000000000064
[...]
RIP: 0010:cdev_del+0x4/0x20
[...]
Call Trace:
tty_unregister_device+0x34/0x50
hso_probe+0x1d1/0x57e [hso]

Fixes: 72dc1c096c70 ("HSO: add option hso driver")
Cc: stable@vger.kernel.org # 2.6.27
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/net/usb/hso.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index cfad5b36bd8e..81ff54e9587f 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2710,14 +2710,14 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface,

serial = kzalloc(sizeof(*serial), GFP_KERNEL);
if (!serial)
- goto exit;
+ goto err_free_dev;

hso_dev->port_data.dev_serial = serial;
serial->parent = hso_dev;

if (hso_serial_common_create
(serial, 1, CTRL_URB_RX_SIZE, CTRL_URB_TX_SIZE))
- goto exit;
+ goto err_free_serial;

serial->tx_data_length--;
serial->write_data = hso_mux_serial_write_data;
@@ -2733,11 +2733,9 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface,
/* done, return it */
return hso_dev;

-exit:
- if (serial) {
- tty_unregister_device(tty_drv, serial->minor);
- kfree(serial);
- }
+err_free_serial:
+ kfree(serial);
+err_free_dev:
kfree(hso_dev);
return NULL;

--
2.26.3
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