From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,T_DKIMWL_WL_HIGH, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id B946FC5CFF1 for ; Tue, 12 Jun 2018 16:47:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FAD0208B0 for ; Tue, 12 Jun 2018 16:47:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="C3uV9PAU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6FAD0208B0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934348AbeFLQrd (ORCPT ); Tue, 12 Jun 2018 12:47:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:59666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933748AbeFLQra (ORCPT ); Tue, 12 Jun 2018 12:47:30 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 85558208B8; Tue, 12 Jun 2018 16:47:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528822050; bh=CfpaETPQeJUTO8uTSICYmTCFAC28FY/SUKzf7BdGqy0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C3uV9PAUkzYGfFKgWH0/mJ4EM3//BWbqEj/Ugfz0yJyrPMOy81ymWLbmtkGFc9SIh RxKnMd6dnUBpuSxRko6C+ROvbzBmEEqQ3kmAz0zikElulHxIfXM49VUK5/Ok3pPIGh 2Ax0gHwk3sTZzoMWAPTmrDpCkUUn6FeDUhsb60nk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tariq Toukan , Willem de Bruijn , Soheil Hassas Yeganeh , "David S. Miller" Subject: [PATCH 4.9 18/31] packet: fix reserve calculation Date: Tue, 12 Jun 2018 18:46:21 +0200 Message-Id: <20180612164621.514099465@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180612164620.797338191@linuxfoundation.org> References: <20180612164620.797338191@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn [ Upstream commit 9aad13b087ab0a588cd68259de618f100053360e ] Commit b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation") ensures that packet_snd always starts writing the link layer header in reserved headroom allocated for this purpose. This is needed because packets may be shorter than hard_header_len, in which case the space up to hard_header_len may be zeroed. But that necessary padding is not accounted for in skb->len. The fix, however, is buggy. It calls skb_push, which grows skb->len when moving skb->data back. But in this case packet length should not change. Instead, call skb_reserve, which moves both skb->data and skb->tail back, without changing length. Fixes: b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation") Reported-by: Tariq Toukan Signed-off-by: Willem de Bruijn Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2918,7 +2918,7 @@ static int packet_snd(struct socket *soc if (unlikely(offset < 0)) goto out_free; } else if (reserve) { - skb_push(skb, reserve); + skb_reserve(skb, -reserve); } /* Returns -EFAULT on error */