diff options
| author | Ahmed S. Darwish <ahmed.darwish@valeo.com> | 2015-01-05 18:49:10 +0100 |
|---|---|---|
| committer | Marc Kleine-Budde <mkl@pengutronix.de> | 2015-01-15 16:58:00 +0100 |
| commit | b442723fcec445fb0ae1104888dd22cd285e0a91 (patch) | |
| tree | 76164d09f5a3830f7e6dddb1ec9a93129c28b903 /drivers/net/can/usb | |
| parent | can: c_can: use regmap_update_bits() to modify RAMINIT register (diff) | |
| download | linux-b442723fcec445fb0ae1104888dd22cd285e0a91.tar.xz linux-b442723fcec445fb0ae1104888dd22cd285e0a91.zip | |
can: kvaser_usb: Don't free packets when tight on URBs
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>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers/net/can/usb')
| -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 541fb7a05625..2e7d513a7c11 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -1294,12 +1294,14 @@ 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; } @@ -1334,6 +1336,7 @@ 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; @@ -1364,9 +1367,6 @@ 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); @@ -1388,8 +1388,6 @@ releasebuf: kfree(buf); nobufmem: usb_free_urb(urb); -nourbmem: - dev_kfree_skb(skb); return ret; } |