Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754911AbcDYPZL (ORCPT ); Mon, 25 Apr 2016 11:25:11 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:33176 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754745AbcDYPZI (ORCPT ); Mon, 25 Apr 2016 11:25:08 -0400 From: To: , CC: Felipe Balbi , Greg Kroah-Hartman , Mike Looijmans , Robert Baldyga , Jim Baxter , Mark Craske Subject: [PATCH v1 1/1] usb: gadget: NCM: NULL pointer dereference in eth_start_xmit Date: Mon, 25 Apr 2016 16:25:03 +0100 Message-ID: <1461597903-17788-1-git-send-email-jim_baxter@mentor.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1293 Lines: 39 From: Jim Baxter "Unable to handle kernel NULL pointer dereference at virtual address 00000078" is reported with "PC is at eth_start_xmit+0x19c/0x378 [u_ether]" The failure scenario is seen when closing the NCM connection while the TCP/IPv6 stack is still trying to transmit over NCM. Defensive code is missing from commit 6d3865f9d41f15ddbcecaa6722871fc0db21d7ab "usb: gadget: NCM: Add transmit multi-frame." Add check for non-NULL dev->port_usb before accessing dev->port_usb->supports_multi_frame. Signed-off-by: Mark Craske Signed-off-by: Jim Baxter --- drivers/usb/gadget/function/u_ether.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 637809e..68f0b7b 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -556,7 +556,8 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb, /* Multi frame CDC protocols may store the frame for * later which is not a dropped frame. */ - if (dev->port_usb->supports_multi_frame) + if (dev->port_usb && + dev->port_usb->supports_multi_frame) goto multiframe; goto drop; } -- 1.9.1