From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hughes Subject: [PATCH] smsc95xx: Use skb_cow to deal with cloned skbs Date: Tue, 18 Apr 2017 15:48:57 +0100 Message-ID: <20170418144857.7810-1-james.hughes@raspberrypi.org> Cc: James Hughes To: netdev@vger.kernel.org, Steve Glendinning , Microchip Linux Driver Support Return-path: Received: from mx08-00252a01.pphosted.com ([91.207.212.211]:60227 "EHLO mx08-00252a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751300AbdDROtO (ORCPT ); Tue, 18 Apr 2017 10:49:14 -0400 Received: from pps.filterd (m0102629.ppops.net [127.0.0.1]) by mx08-00252a01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3IEh44P031598 for ; Tue, 18 Apr 2017 15:49:12 +0100 Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by mx08-00252a01.pphosted.com with ESMTP id 29u80f9jnt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=OK) for ; Tue, 18 Apr 2017 15:49:12 +0100 Received: by mail-wr0-f198.google.com with SMTP id f13so19149822wrf.3 for ; Tue, 18 Apr 2017 07:49:12 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: The driver was failing to check that the SKB wasn't cloned before adding checksum data or adding header data. Replace existing handling to extend the buffer with skb_cow. Don't use skb_cow_head as the sw checksum code modifies the data portion. Signed-off-by: James Hughes --- drivers/net/usb/smsc95xx.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index df60c98..04f6397 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -2067,13 +2067,9 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev, /* We do not advertise SG, so skbs should be already linearized */ BUG_ON(skb_shinfo(skb)->nr_frags); - if (skb_headroom(skb) < overhead) { - struct sk_buff *skb2 = skb_copy_expand(skb, - overhead, 0, flags); - dev_kfree_skb_any(skb); - skb = skb2; - if (!skb) - return NULL; + /* Make writable and expand space by overhead if required */ + if (skb_cow(skb, overhead)) { + return NULL; } if (csum) { -- 2.9.3