Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932237AbaLWPrH (ORCPT ); Tue, 23 Dec 2014 10:47:07 -0500 Received: from mail-wi0-f181.google.com ([209.85.212.181]:46047 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaLWPrF (ORCPT ); Tue, 23 Dec 2014 10:47:05 -0500 Date: Tue, 23 Dec 2014 17:46:54 +0200 From: "Ahmed S. Darwish" To: Olivier Sobrie , Oliver Hartkopp , Wolfgang Grandegger , Marc Kleine-Budde Cc: "David S. Miller" , Paul Gortmaker , Linux-CAN , netdev , LKML Subject: [PATCH] can: kvaser_usb: Don't free packets when tight on URBs Message-ID: <20141223154654.GB6460@vivalin-002> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ahmed S. Darwish 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. Signed-off-by: Ahmed S. Darwish --- drivers/net/can/usb/kvaser_usb.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (Generated over 3.19.0-rc1) diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c index 541fb7a..34c35d8 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -1286,6 +1286,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb, struct kvaser_msg *msg; int i, err; int ret = NETDEV_TX_OK; + bool kfree_skb_on_error = true; if (can_dropped_invalid_skb(netdev, skb)) return NETDEV_TX_OK; @@ -1336,6 +1337,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb, if (!context) { netdev_warn(netdev, "cannot find free context\n"); + kfree_skb_on_error = false; ret = NETDEV_TX_BUSY; goto releasebuf; } @@ -1364,8 +1366,7 @@ 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) */ + kfree_skb_on_error = false; atomic_dec(&priv->active_tx_urbs); usb_unanchor_urb(urb); @@ -1389,7 +1390,8 @@ releasebuf: nobufmem: usb_free_urb(urb); nourbmem: - dev_kfree_skb(skb); + if (kfree_skb_on_error) + dev_kfree_skb(skb); return ret; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/