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=-18.8 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=unavailable 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 486CCC433E0 for ; Fri, 5 Mar 2021 12:43:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D0DF65026 for ; Fri, 5 Mar 2021 12:43:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233424AbhCEMnQ (ORCPT ); Fri, 5 Mar 2021 07:43:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:59160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233906AbhCEMmi (ORCPT ); Fri, 5 Mar 2021 07:42:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1FF136501F; Fri, 5 Mar 2021 12:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614948155; bh=nPt+uSCKZ3h6N89q2fDnwAWYSXzpQYeE8nURH36c4fY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ssAiloUzuWLMqqUpLGS+UCq5QQWt0nkFZgU3Hczbd8yCGrZ/588RT+chd6AbvyajM /bU+lwmmwZLAD2TaTWPIAS4UlGDBubRtO6x2OaXHu27BxbMFgS0nTb6ZtnDdZpShsQ J3M+KiXl4Thyt9KIHKtta/Psxt6bg0nDF7DbkJko= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+7b99aafdcc2eedea6178@syzkaller.appspotmail.com, Eric Dumazet , Marco Elver , Jakub Kicinski Subject: [PATCH 4.9 21/41] net: fix up truesize of cloned skb in skb_prepare_for_shift() Date: Fri, 5 Mar 2021 13:22:28 +0100 Message-Id: <20210305120852.339523244@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120851.255002428@linuxfoundation.org> References: <20210305120851.255002428@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marco Elver commit 097b9146c0e26aabaa6ff3e5ea536a53f5254a79 upstream. Avoid the assumption that ksize(kmalloc(S)) == ksize(kmalloc(S)): when cloning an skb, save and restore truesize after pskb_expand_head(). This can occur if the allocator decides to service an allocation of the same size differently (e.g. use a different size class, or pass the allocation on to KFENCE). Because truesize is used for bookkeeping (such as sk_wmem_queued), a modified truesize of a cloned skb may result in corrupt bookkeeping and relevant warnings (such as in sk_stream_kill_queues()). Link: https://lkml.kernel.org/r/X9JR/J6dMMOy1obu@elver.google.com Reported-by: syzbot+7b99aafdcc2eedea6178@syzkaller.appspotmail.com Suggested-by: Eric Dumazet Signed-off-by: Marco Elver Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20210201160420.2826895-1-elver@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/skbuff.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2673,7 +2673,19 @@ EXPORT_SYMBOL(skb_split); */ static int skb_prepare_for_shift(struct sk_buff *skb) { - return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC); + int ret = 0; + + if (skb_cloned(skb)) { + /* Save and restore truesize: pskb_expand_head() may reallocate + * memory where ksize(kmalloc(S)) != ksize(kmalloc(S)), but we + * cannot change truesize at this point. + */ + unsigned int save_truesize = skb->truesize; + + ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC); + skb->truesize = save_truesize; + } + return ret; } /**