From: Johan Hovold <jhovold@gmail.com>
Date: Tue, 22 Mar 2011 10:12:11 +0000 (+0100)
Subject: USB: cdc-acm: fix potential null-pointer dereference on disconnect
X-Git-Tag: v2.6.27.59~63
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=12337de3c931a6352cf04db4dcfa279a35ed9f53;p=thirdparty%2Fkernel%2Fstable.git

USB: cdc-acm: fix potential null-pointer dereference on disconnect

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@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index a250caecab915..ee80c5dc85664 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -285,6 +285,8 @@ 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) {
 
@@ -319,7 +321,6 @@ 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)
 		err ("%s - usb_submit_urb failed with result %d",