lkml.org 
[lkml]   [2012]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[ 23/54] usbnet: fix skb traversing races during unlink(v2)
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ming Lei <tom.leiming@gmail.com>

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 <huajun.li.lee@gmail.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/usb/usbnet.c | 54 +++++++++++++++++++++++++++++++--------------
include/linux/usb/usbnet.h | 3 +-
2 files changed, 40 insertions(+), 17 deletions(-)

--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -277,17 +277,32 @@ int usbnet_change_mtu (struct net_device
}
EXPORT_SYMBOL_GPL(usbnet_change_mtu);

+/* The caller must hold list->lock */
+static void __usbnet_queue_skb(struct sk_buff_head *list,
+ struct sk_buff *newsk, enum skb_state state)
+{
+ struct skb_data *entry = (struct skb_data *) newsk->cb;
+
+ __skb_queue_tail(list, newsk);
+ entry->state = state;
+}
+
/*-------------------------------------------------------------------------*/

/* some LK 2.4 HCDs oopsed if we freed or resubmitted urbs from
* completion callbacks. 2.5 should have fixed those bugs...
*/

-static void defer_bh(struct usbnet *dev, struct sk_buff *skb, struct sk_buff_head *list)
+static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
+ struct sk_buff_head *list, enum skb_state state)
{
unsigned long flags;
+ enum skb_state old_state;
+ struct skb_data *entry = (struct skb_data *) skb->cb;

spin_lock_irqsave(&list->lock, flags);
+ old_state = entry->state;
+ entry->state = state;
__skb_unlink(skb, list);
spin_unlock(&list->lock);
spin_lock(&dev->done.lock);
@@ -295,6 +310,7 @@ static void defer_bh(struct usbnet *dev,
if (dev->done.qlen == 1)
tasklet_schedule(&dev->bh);
spin_unlock_irqrestore(&dev->done.lock, flags);
+ return old_state;
}

/* some work can't be done in tasklets, so we use keventd
@@ -335,7 +351,6 @@ static int rx_submit (struct usbnet *dev
entry = (struct skb_data *) skb->cb;
entry->urb = urb;
entry->dev = dev;
- entry->state = rx_start;
entry->length = 0;

usb_fill_bulk_urb (urb, dev->udev, dev->in,
@@ -367,7 +382,7 @@ static int rx_submit (struct usbnet *dev
tasklet_schedule (&dev->bh);
break;
case 0:
- __skb_queue_tail (&dev->rxq, skb);
+ __usbnet_queue_skb(&dev->rxq, skb, rx_start);
}
} else {
netif_dbg(dev, ifdown, dev->net, "rx: stopped\n");
@@ -418,16 +433,17 @@ static void rx_complete (struct urb *urb
struct skb_data *entry = (struct skb_data *) skb->cb;
struct usbnet *dev = entry->dev;
int urb_status = urb->status;
+ enum skb_state state;

skb_put (skb, urb->actual_length);
- entry->state = rx_done;
+ state = rx_done;
entry->urb = NULL;

switch (urb_status) {
/* success */
case 0:
if (skb->len < dev->net->hard_header_len) {
- entry->state = rx_cleanup;
+ state = rx_cleanup;
dev->net->stats.rx_errors++;
dev->net->stats.rx_length_errors++;
netif_dbg(dev, rx_err, dev->net,
@@ -466,7 +482,7 @@ static void rx_complete (struct urb *urb
"rx throttle %d\n", urb_status);
}
block:
- entry->state = rx_cleanup;
+ state = rx_cleanup;
entry->urb = urb;
urb = NULL;
break;
@@ -477,17 +493,18 @@ block:
// FALLTHROUGH

default:
- entry->state = rx_cleanup;
+ state = rx_cleanup;
dev->net->stats.rx_errors++;
netif_dbg(dev, rx_err, dev->net, "rx status %d\n", urb_status);
break;
}

- defer_bh(dev, skb, &dev->rxq);
+ state = defer_bh(dev, skb, &dev->rxq, state);

if (urb) {
if (netif_running (dev->net) &&
- !test_bit (EVENT_RX_HALT, &dev->flags)) {
+ !test_bit (EVENT_RX_HALT, &dev->flags) &&
+ state != unlink_start) {
rx_submit (dev, urb, GFP_ATOMIC);
return;
}
@@ -573,16 +590,23 @@ EXPORT_SYMBOL_GPL(usbnet_purge_paused_rx
static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q)
{
unsigned long flags;
- struct sk_buff *skb, *skbnext;
+ struct sk_buff *skb;
int count = 0;

spin_lock_irqsave (&q->lock, flags);
- skb_queue_walk_safe(q, skb, skbnext) {
+ while (!skb_queue_empty(q)) {
struct skb_data *entry;
struct urb *urb;
int retval;

- entry = (struct skb_data *) skb->cb;
+ skb_queue_walk(q, skb) {
+ entry = (struct skb_data *) skb->cb;
+ if (entry->state != unlink_start)
+ goto found;
+ }
+ break;
+found:
+ entry->state = unlink_start;
urb = entry->urb;

/*
@@ -1033,8 +1057,7 @@ static void tx_complete (struct urb *urb
}

usb_autopm_put_interface_async(dev->intf);
- entry->state = tx_done;
- defer_bh(dev, skb, &dev->txq);
+ (void) defer_bh(dev, skb, &dev->txq, tx_done);
}

/*-------------------------------------------------------------------------*/
@@ -1087,7 +1110,6 @@ netdev_tx_t usbnet_start_xmit (struct sk
entry = (struct skb_data *) skb->cb;
entry->urb = urb;
entry->dev = dev;
- entry->state = tx_start;
entry->length = length;

usb_fill_bulk_urb (urb, dev->udev, dev->out,
@@ -1146,7 +1168,7 @@ netdev_tx_t usbnet_start_xmit (struct sk
break;
case 0:
net->trans_start = jiffies;
- __skb_queue_tail (&dev->txq, skb);
+ __usbnet_queue_skb(&dev->txq, skb, tx_start);
if (dev->txq.qlen >= TX_QLEN (dev))
netif_stop_queue (net);
}
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -191,7 +191,8 @@ extern void usbnet_cdc_status(struct usb
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 */



\
 
 \ /
  Last update: 2012-05-19 02:21    [W:0.323 / U:9.432 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site