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=-8.6 required=3.0 tests=DATE_IN_PAST_06_12, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 B3A7FC7618B for ; Thu, 25 Jul 2019 05:48:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 888A22075C for ; Thu, 25 Jul 2019 05:48:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564033714; bh=IU+gfeR+aLvaSZLrw3bgYBQUZrP95fI/FfqM3PaKlpA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=D/3GPe2YWoZ57wcJ9OYLY68XsCcmeEVqpdEaP8zRwvzvZLYzYyolauyzaQ7BuUztf nD4pxDbZFavXWJ15QrmNc27xPEwnayNSo3u6Uo0i0sCs7OnabYLLLZv0WJlZHMQpfu h60OL9A34OHiDimdQsXwqJV8najkH/OAUi94HX3I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405250AbfGYFpr (ORCPT ); Thu, 25 Jul 2019 01:45:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:33168 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405248AbfGYFpq (ORCPT ); Thu, 25 Jul 2019 01:45:46 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 8AB0C22BEB; Thu, 25 Jul 2019 05:45:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564033545; bh=IU+gfeR+aLvaSZLrw3bgYBQUZrP95fI/FfqM3PaKlpA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Sv1WponBClx90xJIOvlpkoUmHjEOGNWBQpAAJRA+Y79YOyE4XKA6W0s4fM7NNd8XF Y6lhfbc6IpgbTQhFNp0JvxIjFentWVwaUmMIDQ3L9SODYcvwbuj+WDN16LGJEQjySg U7iDnR+fIsZ9uryty9r03uwXV6WixRC4svoxl0CQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Darrick J. Wong" , Christoph Hellwig , Amir Goldstein , Luis Chamberlain , Sasha Levin Subject: [PATCH 4.19 244/271] xfs: dont overflow xattr listent buffer Date: Wed, 24 Jul 2019 21:21:53 +0200 Message-Id: <20190724191716.093741873@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190724191655.268628197@linuxfoundation.org> References: <20190724191655.268628197@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 3b50086f0c0d78c144d9483fa292c1509c931b70 upstream. For VFS listxattr calls, xfs_xattr_put_listent calls __xfs_xattr_put_listent twice if it sees an attribute "trusted.SGI_ACL_FILE": once for that name, and again for "system.posix_acl_access". Unfortunately, if we happen to run out of buffer space while emitting the first name, we set count to -1 (so that we can feed ERANGE to the caller). The second invocation doesn't check that the context parameters make sense and overwrites the byte before the buffer, triggering a KASAN report: ================================================================== BUG: KASAN: slab-out-of-bounds in strncpy+0xb3/0xd0 Write of size 1 at addr ffff88807fbd317f by task syz/1113 CPU: 3 PID: 1113 Comm: syz Not tainted 5.0.0-rc6-xfsx #rc6 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0xcc/0x180 print_address_description+0x6c/0x23c kasan_report.cold.3+0x1c/0x35 strncpy+0xb3/0xd0 __xfs_xattr_put_listent+0x1a9/0x2c0 [xfs] xfs_attr_list_int_ilocked+0x11af/0x1800 [xfs] xfs_attr_list_int+0x20c/0x2e0 [xfs] xfs_vn_listxattr+0x225/0x320 [xfs] listxattr+0x11f/0x1b0 path_listxattr+0xbd/0x130 do_syscall_64+0x139/0x560 While we're at it we add an assert to the other put_listent to avoid this sort of thing ever happening to the attrlist_by_handle code. Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Suggested-by: Amir Goldstein Reviewed-by: Amir Goldstein Signed-off-by: Luis Chamberlain Signed-off-by: Sasha Levin --- fs/xfs/xfs_attr_list.c | 1 + fs/xfs/xfs_xattr.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c index a58034049995..3d213a7394c5 100644 --- a/fs/xfs/xfs_attr_list.c +++ b/fs/xfs/xfs_attr_list.c @@ -555,6 +555,7 @@ xfs_attr_put_listent( attrlist_ent_t *aep; int arraytop; + ASSERT(!context->seen_enough); ASSERT(!(context->flags & ATTR_KERNOVAL)); ASSERT(context->count >= 0); ASSERT(context->count < (ATTR_MAX_VALUELEN/8)); diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c index 63ee1d5bf1d7..9a63016009a1 100644 --- a/fs/xfs/xfs_xattr.c +++ b/fs/xfs/xfs_xattr.c @@ -129,6 +129,9 @@ __xfs_xattr_put_listent( char *offset; int arraytop; + if (context->count < 0 || context->seen_enough) + return; + if (!context->alist) goto compute_size; -- 2.20.1