From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hughes Subject: [PATCH v4] smsc95xx: Use skb_cow_head to deal with cloned skbs Date: Wed, 19 Apr 2017 11:13:40 +0100 Message-ID: <20170419101340.27929-1-james.hughes@raspberrypi.org> Cc: James Hughes To: netdev@vger.kernel.org, Steve Glendinning , Microchip Linux Driver Support Return-path: Received: from mx07-00252a01.pphosted.com ([62.209.51.214]:62471 "EHLO mx07-00252a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761917AbdDSKNp (ORCPT ); Wed, 19 Apr 2017 06:13:45 -0400 Received: from pps.filterd (m0102628.ppops.net [127.0.0.1]) by mx07-00252a01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3JAAZ22015352 for ; Wed, 19 Apr 2017 11:13:43 +0100 Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by mx07-00252a01.pphosted.com with ESMTP id 29wqp2r9s9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=OK) for ; Wed, 19 Apr 2017 11:13:43 +0100 Received: by mail-wr0-f198.google.com with SMTP id p111so1943914wrc.10 for ; Wed, 19 Apr 2017 03:13:43 -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. Replace existing handling to extend/copy the header buffer with skb_cow_head. Signed-off-by: James Hughes --- Changes v3 - Added the dev_kfree_skb_any call to ensure skb is deallocated as when returning NULL the caller won't deallocate v4 - Fix typo in comment (reallocate to deallocate) drivers/net/usb/smsc95xx.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index df60c98..f6661e3 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -2067,13 +2067,13 @@ 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); + /* Make writable and expand header space by overhead if required */ + if (skb_cow_head(skb, overhead)) { + /* Must deallocate here as returning NULL to indicate error + * means the skb won't be deallocated in the caller. + */ dev_kfree_skb_any(skb); - skb = skb2; - if (!skb) - return NULL; + return NULL; } if (csum) { -- 2.9.3