From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Holger Eitzenberger , "David S. Miller" Subject: [ 064/102] asix: fix BUG in receive path when lowering MTU Date: Fri, 17 May 2013 14:36:19 -0700 Message-Id: <20130517213251.116419900@linuxfoundation.org> In-Reply-To: <20130517213244.277411019@linuxfoundation.org> References: <20130517213244.277411019@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: "holger@eitzenberger.org" [ Upstream commit c5060cec6ba27ad3f0e7facfdf05d2f18e3e3010 ] There is bug in the receive path of the asix driver at the time a packet is received larger than MTU size and DF bit set: BUG: unable to handle kernel paging request at 0000004000000001 IP: [] skb_release_head_state+0x2d/0xd2 ... Call Trace: [] ? skb_release_all+0x9/0x1e [] ? __kfree_skb+0x9/0x6f [] ? asix_rx_fixup_internal+0xff/0x1ae [asix] [] ? usbnet_bh+0x4f/0x226 [usbnet] ... It is easily reproducable by setting an MTU of 512 e. g. and sending something like ping -s 1472 -c 1 -M do $SELF from another box. And this is because the rx->ax_skb is freed on error, but rx->ax_skb is not reset, and the size is not reset to zero in this case. And since the skb is added again to the usbnet->done skb queue it is accessing already freed memory, resulting in the BUG when freeing a 2nd time. I therefore think the value 0x0000004000000001 show in the trace is more or less random data. Signed-off-by: Holger Eitzenberger Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/asix_common.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/net/usb/asix_common.c +++ b/drivers/net/usb/asix_common.c @@ -100,6 +100,9 @@ int asix_rx_fixup_internal(struct usbnet netdev_err(dev->net, "asix_rx_fixup() Bad RX Length %d\n", rx->size); kfree_skb(rx->ax_skb); + rx->ax_skb = NULL; + rx->size = 0U; + return 0; }