This is a note to let you know that I've just added the patch titled
usbnet: increase URB reference count before usb_unlink_urb
to the 3.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usbnet-increase-urb-reference-count-before-usb_unlink_urb.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 0956a8c20b23d429e79ff86d4325583fc06f9eb4 Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Thu, 22 Mar 2012 03:22:18 +0000
Subject: usbnet: increase URB reference count before usb_unlink_urb
From: "[email protected]" <[email protected]>
commit 0956a8c20b23d429e79ff86d4325583fc06f9eb4 upstream.
Commit 4231d47e6fe69f061f96c98c30eaf9fb4c14b96d(net/usbnet: avoid
recursive locking in usbnet_stop()) fixes the recursive locking
problem by releasing the skb queue lock, but it makes usb_unlink_urb
racing with defer_bh, and the URB to being unlinked may be freed before
or during calling usb_unlink_urb, so use-after-free problem may be
triggerd inside usb_unlink_urb.
The patch fixes the use-after-free problem by increasing URB
reference count with skb queue lock held before calling
usb_unlink_urb, so the URB won't be freed until return from
usb_unlink_urb.
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Alan Stern <[email protected]>
Cc: Oliver Neukum <[email protected]>
Reported-by: Dave Jones <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/usb/usbnet.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -589,6 +589,14 @@ static int unlink_urbs (struct usbnet *d
entry = (struct skb_data *) skb->cb;
urb = entry->urb;
+ /*
+ * Get reference count of the URB to avoid it to be
+ * freed during usb_unlink_urb, which may trigger
+ * use-after-free problem inside usb_unlink_urb since
+ * usb_unlink_urb is always racing with .complete
+ * handler(include defer_bh).
+ */
+ usb_get_urb(urb);
spin_unlock_irqrestore(&q->lock, flags);
// during some PM-driven resume scenarios,
// these (async) unlinks complete immediately
@@ -597,6 +605,7 @@ static int unlink_urbs (struct usbnet *d
netdev_dbg(dev->net, "unlink urb err, %d\n", retval);
else
count++;
+ usb_put_urb(urb);
spin_lock_irqsave(&q->lock, flags);
}
spin_unlock_irqrestore (&q->lock, flags);
Patches currently in stable-queue which might be from [email protected] are
queue-3.3/usbnet-increase-urb-reference-count-before-usb_unlink_urb.patch
queue-3.3/usbnet-don-t-clear-urb-dev-in-tx_complete.patch
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