From patchwork Mon Feb 8 15:00:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 379257 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=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85500C433DB for ; Mon, 8 Feb 2021 15:08:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 42B6F64EE0 for ; Mon, 8 Feb 2021 15:08:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229795AbhBHPIJ (ORCPT ); Mon, 8 Feb 2021 10:08:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:52060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232392AbhBHPGT (ORCPT ); Mon, 8 Feb 2021 10:06:19 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id AC6F264EDF; Mon, 8 Feb 2021 15:04:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612796692; bh=R7X3F2Lwr2jEybZesvYA2VbaWLnZKOajyJcZxuiFvDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JT/ZfHXwSPXdNlKaQsvIj0MN3gHr9Id3optf4bN2BwjiGdJMruNFxTN/mXuvKyb8x K9ndN4ftn0Jpti6u4zbGwTVzTH06lSFpa/ZqLlMqLwnWGZzCRzqW2rnoA3ylAstY89 r1D8+06PN4OMtV8X+26NYXsO46DUxMbVw/dtrT64= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xie He , Martin Schiller , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.9 23/43] net: lapb: Copy the skb before sending a packet Date: Mon, 8 Feb 2021 16:00:49 +0100 Message-Id: <20210208145807.250376835@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145806.281758651@linuxfoundation.org> References: <20210208145806.281758651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xie He [ Upstream commit 88c7a9fd9bdd3e453f04018920964c6f848a591a ] When sending a packet, we will prepend it with an LAPB header. This modifies the shared parts of a cloned skb, so we should copy the skb rather than just clone it, before we prepend the header. In "Documentation/networking/driver.rst" (the 2nd point), it states that drivers shouldn't modify the shared parts of a cloned skb when transmitting. The "dev_queue_xmit_nit" function in "net/core/dev.c", which is called when an skb is being sent, clones the skb and sents the clone to AF_PACKET sockets. Because the LAPB drivers first remove a 1-byte pseudo-header before handing over the skb to us, if we don't copy the skb before prepending the LAPB header, the first byte of the packets received on AF_PACKET sockets can be corrupted. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He Acked-by: Martin Schiller Link: https://lore.kernel.org/r/20210201055706.415842-1-xie.he.0141@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/lapb/lapb_out.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/lapb/lapb_out.c b/net/lapb/lapb_out.c index 482c94d9d958a..d1c7dcc234486 100644 --- a/net/lapb/lapb_out.c +++ b/net/lapb/lapb_out.c @@ -87,7 +87,8 @@ void lapb_kick(struct lapb_cb *lapb) skb = skb_dequeue(&lapb->write_queue); do { - if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { + skbn = skb_copy(skb, GFP_ATOMIC); + if (!skbn) { skb_queue_head(&lapb->write_queue, skb); break; }