From 5b05ac638c39e92f3fa6291b4aebd6fc485320ba Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 26 Apr 2012 11:33:46 +0800 Subject: usbnet: fix skb traversing races during unlink(v2) commit 5b6e9bcdeb65634b4ad604eb4536404bbfc62cfa upstream. Commit 4231d47e6fe69f061f96c98c30eaf9fb4c14b96d(net/usbnet: avoid recursive locking in usbnet_stop()) fixes the recursive locking problem by releasing the skb queue lock before unlink, but may cause skb traversing races: - after URB is unlinked and the queue lock is released, the refered skb and skb->next may be moved to done queue, even be released - in skb_queue_walk_safe, the next skb is still obtained by next pointer of the last skb - so maybe trigger oops or other problems This patch extends the usage of entry->state to describe 'start_unlink' state, so always holding the queue(rx/tx) lock to change the state if the referd skb is in rx or tx queue because we need to know if the refered urb has been started unlinking in unlink_urbs. The other part of this patch is based on Huajun's patch: always traverse from head of the tx/rx queue to get skb which is to be unlinked but not been started unlinking. Signed-off-by: Huajun Li Signed-off-by: Ming Lei Cc: Oliver Neukum Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/usb/usbnet.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index 605b0aa..76f4396 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -191,7 +191,8 @@ extern void usbnet_cdc_status(struct usbnet *, struct urb *); enum skb_state { illegal = 0, tx_start, tx_done, - rx_start, rx_done, rx_cleanup + rx_start, rx_done, rx_cleanup, + unlink_start }; struct skb_data { /* skb->cb is one of these */ -- cgit v1.1