[48/63] USB: cdc-acm: fix potential null-pointer dereference on disconnect

From: Greg KH
Date: Fri Mar 25 2011 - 20:06:03 EST


2.6.38-stable review patch. If anyone has any objections, please let us know.

------------------

From: Johan Hovold <jhovold@xxxxxxxxx>

commit 7e7797e7f6f7bfab73fca02c65e40eaa5bb9000c upstream.

Fix potential null-pointer exception on disconnect introduced by commit
11ea859d64b69a747d6b060b9ed1520eab1161fe (USB: additional power savings
for cdc-acm devices that support remote wakeup).

Only access acm->dev after making sure it is non-null in control urb
completion handler.

Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
drivers/usb/class/cdc-acm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -297,6 +297,8 @@ static void acm_ctrl_irq(struct urb *urb
if (!ACM_READY(acm))
goto exit;

+ usb_mark_last_busy(acm->dev);
+
data = (unsigned char *)(dr + 1);
switch (dr->bNotificationType) {
case USB_CDC_NOTIFY_NETWORK_CONNECTION:
@@ -336,7 +338,6 @@ static void acm_ctrl_irq(struct urb *urb
break;
}
exit:
- usb_mark_last_busy(acm->dev);
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval)
dev_err(&urb->dev->dev, "%s - usb_submit_urb failed with "


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