From patchwork Tue Oct 27 13:49:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 290036 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,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 D16ECC388F9 for ; Tue, 27 Oct 2020 14:28:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CCE322202 for ; Tue, 27 Oct 2020 14:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603808925; bh=Noym+lf8cZ47Ly+mv+s8DXWgLUwSiQZUDXTZQt2zu7A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NEZdTajkzqCuZtzRqTvj0hT20hrKKlVvpOpS7koryHmp7aSoeYVERuq6YgyOH5bdk HLP+qsnzOzpQbPnmQOesEE77nZw/7JGUg5IawY5Ed1DEWAmLXniGGdFraaLk8FLk1m TMXijDlQ2KRpIXaNjm1j31wGr4Ai49fm264YIivM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759276AbgJ0O2o (ORCPT ); Tue, 27 Oct 2020 10:28:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:55194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759271AbgJ0O2n (ORCPT ); Tue, 27 Oct 2020 10:28:43 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 B1701206DC; Tue, 27 Oct 2020 14:28:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603808923; bh=Noym+lf8cZ47Ly+mv+s8DXWgLUwSiQZUDXTZQt2zu7A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LD8xjM+A8gbe1dPr7MkEvVK3E3rJG/AY6kwbJxhB/kaL4y5FGsBL9jp5lj/Uk+lDd y/P+7uys2JnI6+/3teUYabxvZG7BtNglUatIGYb/JnUkJHMWvzBldoNuRR3evCOuts kvLdztFP/l9a/Mxq4+/iXgjq60WkNsbyCSKuG+jk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jon Maloy , Ying Xue , Cong Wang , Xin Long , Jakub Kicinski , syzbot+e96a7ba46281824cc46a@syzkaller.appspotmail.com Subject: [PATCH 5.4 011/408] tipc: fix the skb_unshare() in tipc_buf_append() Date: Tue, 27 Oct 2020 14:49:09 +0100 Message-Id: <20201027135455.577087822@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135455.027547757@linuxfoundation.org> References: <20201027135455.027547757@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Cong Wang [ Upstream commit ed42989eab57d619667d7e87dfbd8fe207db54fe ] skb_unshare() drops a reference count on the old skb unconditionally, so in the failure case, we end up freeing the skb twice here. And because the skb is allocated in fclone and cloned by caller tipc_msg_reassemble(), the consequence is actually freeing the original skb too, thus triggered the UAF by syzbot. Fix this by replacing this skb_unshare() with skb_cloned()+skb_copy(). Fixes: ff48b6222e65 ("tipc: use skb_unshare() instead in tipc_buf_append()") Reported-and-tested-by: syzbot+e96a7ba46281824cc46a@syzkaller.appspotmail.com Cc: Jon Maloy Cc: Ying Xue Signed-off-by: Cong Wang Reviewed-by: Xin Long Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/tipc/msg.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -140,7 +140,8 @@ int tipc_buf_append(struct sk_buff **hea if (fragid == FIRST_FRAGMENT) { if (unlikely(head)) goto err; - frag = skb_unshare(frag, GFP_ATOMIC); + if (skb_cloned(frag)) + frag = skb_copy(frag, GFP_ATOMIC); if (unlikely(!frag)) goto err; head = *headbuf = frag;