2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------ 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: [email protected] 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: Willy Tarreau <[email protected]> --- drivers/net/usb/usbnet.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index da33dce..a92a415 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -584,6 +584,14 @@ static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q) 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 @@ -592,6 +600,7 @@ static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q) devdbg (dev, "unlink urb err, %d", retval); else count++; + usb_put_urb(urb); spin_lock_irqsave(&q->lock, flags); } spin_unlock_irqrestore (&q->lock, flags); -- 1.7.2.1.45.g54fbc -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
