This is a note to let you know that I've just added the patch titled can: kvaser_usb: Don't free packets when tight on URBs to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: can-kvaser_usb-don-t-free-packets-when-tight-on-urbs.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b442723fcec445fb0ae1104888dd22cd285e0a91 Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx> Date: Mon, 5 Jan 2015 12:49:10 -0500 Subject: can: kvaser_usb: Don't free packets when tight on URBs From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/can/usb/kvaser_usb.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- 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 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 } } + /* 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 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; } Patches currently in stable-queue which might be from ahmed.darwish@xxxxxxxxx are queue-3.10/can-kvaser_usb-don-t-send-a-reset_chip-for-non-existing-channels.patch queue-3.10/can-kvaser_usb-reset-all-urb-tx-contexts-upon-channel-close.patch queue-3.10/can-kvaser_usb-don-t-free-packets-when-tight-on-urbs.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html