@@ -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;
}
This is a note to let you know that I have just added a patch titled can: kvaser_usb: Don't free packets when tight on URBs to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt6. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 1ee7512a52429d10c3d6f70f188e43e0842a71c2 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" <ahmed.darwish@valeo.com> Date: Mon, 5 Jan 2015 12:49:10 -0500 Subject: 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: Luis Henriques <luis.henriques@canonical.com> --- drivers/net/can/usb/kvaser_usb.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) -- 2.1.4