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usbnet: fix skb traversing races during unlink(v2)

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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 <huajun.li.lee@gmail.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Cc: Oliver Neukum <oneukum@suse.de>
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ming Lei 2012-04-26 11:33:46 +08:00 • committed by David S. Miller
parent 8aa51d64c1
commit 5b6e9bcdeb
2 changed files with 40 additions and 17 deletions
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3
include/linux/usb/usbnet.h
View file

@ -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 */