From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id AHxnFgLzG1tQYAAAmS7hNA ; Sat, 09 Jun 2018 15:32:42 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 2B85D608CD; Sat, 9 Jun 2018 15:32:42 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="PU/xlQ/8" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,T_DKIMWL_WL_HIGH autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 88512608BF; Sat, 9 Jun 2018 15:32:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 88512608BF Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932533AbeFIPck (ORCPT + 25 others); Sat, 9 Jun 2018 11:32:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:35014 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932463AbeFIPcf (ORCPT ); Sat, 9 Jun 2018 11:32:35 -0400 Received: from localhost (D57E6652.static.ziggozakelijk.nl [213.126.102.82]) (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 8F17F208A3; Sat, 9 Jun 2018 15:32:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528558355; bh=ZIuMqUsbc8gEoLqUET3MDHshc2TZt6Jlg4aAByOwem8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PU/xlQ/8mghFzcnnNhaYCp0d9PVwLP+1O0raKK7bw+2NsEDvNjiwk8yZl9LyUnEB8 eCchNTIIo2b41NtDRSNtxXvbbXZOYjYehWHzNsLOBZy7cO+OttDrvDM4Q9LlHxgiXt /1tyRp/HnKU1RgvWLohNK+F1KyjjRbxG9kbwTFb8= 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 4.16 26/48] packet: fix reserve calculation Date: Sat, 9 Jun 2018 17:29:38 +0200 Message-Id: <20180609145949.406980082@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180609145947.679103414@linuxfoundation.org> References: <20180609145947.679103414@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 4.16-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 @@ -2911,7 +2911,7 @@ 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 */