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authorAhmed S. Darwish <ahmed.darwish@valeo.com>2015-01-05 12:49:10 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-27 08:18:57 -0800
commit6ab8d4d1eb6a7db792397e4a6a61a5a0a51a7411 (patch)
treeee4f54505ca5523ddeacaa5fb5683ad0b8990cdd
parent97ab28073bcc3299080bbaba025861d053e70f43 (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>
-rw-r--r--drivers/net/can/usb/kvaser_usb.c10
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 e77d11049747..16ba387ea5cc 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -1285,12 +1285,14 @@ 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;
}
@@ -1325,6 +1327,7 @@ 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;
@@ -1355,9 +1358,6 @@ 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);
@@ -1379,8 +1379,6 @@ releasebuf:
kfree(buf);
nobufmem:
usb_free_urb(urb);
-nourbmem:
- dev_kfree_skb(skb);
return ret;
}