diff options
| author | Ahmed S. Darwish <ahmed.darwish@valeo.com> | 2015-01-05 12:49:10 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-27 07:52:32 -0800 |
| commit | 853a4bc8853520f75d0b35fc0b0951eb6999b58a (patch) | |
| tree | 2f8520066cbffa6b6293c61b7f3ad08050340429 /drivers | |
| parent | b9e33b264083ffd7d9d2ad301c3c336e7519a99f (diff) | |
can: kvaser_usb: Don't free packets when tight on URBs
commit b442723fcec445fb0ae1104888dd22cd285e0a91 upstream.
Flooding the Kvaser CAN to USB dongle with multiple reads and
writes in high frequency caused seemingly-random panics in the
kernel.
On further inspection, it seems the driver erroneously freed the
to-be-transmitted packet upon getting tight on URBs and returning
NETDEV_TX_BUSY, leading to invalid memory writes and double frees
at a later point in time.
Note:
Finding no more URBs/transmit-contexts and returning NETDEV_TX_BUSY
is a driver bug in and out of itself: it means that our start/stop
queue flow control is broken.
This patch only fixes the (buggy) error handling code; the root
cause shall be fixed in a later commit.
Acked-by: Olivier Sobrie <olivier@sobrie.be>
Signed-off-by: Ahmed S. Darwish <ahmed.darwish@valeo.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/can/usb/kvaser_usb.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c index cc3df8aebb87..f6e30be1c0eb 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -1286,12 +1286,14 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb, if (!urb) { netdev_err(netdev, "No memory left for URBs\n"); stats->tx_dropped++; - goto nourbmem; + dev_kfree_skb(skb); + return NETDEV_TX_OK; } buf = kmalloc(sizeof(struct kvaser_msg), GFP_ATOMIC); if (!buf) { stats->tx_dropped++; + dev_kfree_skb(skb); goto nobufmem; } @@ -1326,6 +1328,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb, } } + /* This should never happen; it implies a flow control bug */ if (!context) { netdev_warn(netdev, "cannot find free context\n"); ret = NETDEV_TX_BUSY; @@ -1356,9 +1359,6 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb, if (unlikely(err)) { can_free_echo_skb(netdev, context->echo_index); - skb = NULL; /* set to NULL to avoid double free in - * dev_kfree_skb(skb) */ - atomic_dec(&priv->active_tx_urbs); usb_unanchor_urb(urb); @@ -1380,8 +1380,6 @@ releasebuf: kfree(buf); nobufmem: usb_free_urb(urb); -nourbmem: - dev_kfree_skb(skb); return ret; } |