[PATCH 111/173] USB: cdc-acm: fix potential null-pointer dereference on disconnect

[Willy Tarreau]

2.6.27.59-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(-)

Index: longterm-2.6.27/drivers/usb/class/cdc-acm.c
===================================================================
--- longterm-2.6.27.orig/drivers/usb/class/cdc-acm.c	2011-01-23 10:52:26.000000000 +0100
+++ longterm-2.6.27/drivers/usb/class/cdc-acm.c	2011-04-25 16:30:06.372280691 +0200
@@ -285,6 +285,8 @@
 	if (!ACM_READY(acm))
 		goto exit;
 
+	usb_mark_last_busy(acm->dev);
+
 	data = (unsigned char *)(dr + 1);
 	switch (dr->bNotificationType) {
 
@@ -319,7 +321,6 @@
 			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",


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