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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C276C4167D for ; Wed, 6 Apr 2022 01:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1839475AbiDFBDs (ORCPT ); Tue, 5 Apr 2022 21:03:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354815AbiDEKQF (ORCPT ); Tue, 5 Apr 2022 06:16:05 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DD084A3EF; Tue, 5 Apr 2022 03:02:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id CBFFAB81B7A; Tue, 5 Apr 2022 10:02:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21C59C385A2; Tue, 5 Apr 2022 10:02:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649152974; bh=gXLc8Nmru/OE480BeQnP0EBfJ2//XCu6TqSqJ64TlP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2RwB5jSvOXwXzDawimK4mPbEfTbW9VyQPQ9WmDkkuPFwkNOINCYkVLkQNNdwsh2VQ xxNfZl2HGMLA8YfWCZ+iEwgb898ilZu2yZk+1oRyP50x/xMbCBgoQ8Q/4MdugeeeVq pydvHxcZJhBYPQJMBw5YRbEi/aQCj2/gHNCHb5io= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hulk Robot , Baokun Li , Richard Weinberger Subject: [PATCH 5.10 056/599] jffs2: fix use-after-free in jffs2_clear_xattr_subsystem Date: Tue, 5 Apr 2022 09:25:50 +0200 Message-Id: <20220405070300.494430291@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070258.802373272@linuxfoundation.org> References: <20220405070258.802373272@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: Baokun Li commit 4c7c44ee1650677fbe89d86edbad9497b7679b5c upstream. When we mount a jffs2 image, assume that the first few blocks of the image are normal and contain at least one xattr-related inode, but the next block is abnormal. As a result, an error is returned in jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then called in jffs2_build_filesystem() and then again in jffs2_do_fill_super(). Finally we can observe the following report: ================================================================== BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac Read of size 8 at addr ffff8881243384e0 by task mount/719 Call Trace: dump_stack+0x115/0x16b jffs2_clear_xattr_subsystem+0x95/0x6ac jffs2_do_fill_super+0x84f/0xc30 jffs2_fill_super+0x2ea/0x4c0 mtd_get_sb+0x254/0x400 mtd_get_sb_by_nr+0x4f/0xd0 get_tree_mtd+0x498/0x840 jffs2_get_tree+0x25/0x30 vfs_get_tree+0x8d/0x2e0 path_mount+0x50f/0x1e50 do_mount+0x107/0x130 __se_sys_mount+0x1c5/0x2f0 __x64_sys_mount+0xc7/0x160 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Allocated by task 719: kasan_save_stack+0x23/0x60 __kasan_kmalloc.constprop.0+0x10b/0x120 kasan_slab_alloc+0x12/0x20 kmem_cache_alloc+0x1c0/0x870 jffs2_alloc_xattr_ref+0x2f/0xa0 jffs2_scan_medium.cold+0x3713/0x4794 jffs2_do_mount_fs.cold+0xa7/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] Freed by task 719: kmem_cache_free+0xcc/0x7b0 jffs2_free_xattr_ref+0x78/0x98 jffs2_clear_xattr_subsystem+0xa1/0x6ac jffs2_do_mount_fs.cold+0x5e6/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] The buggy address belongs to the object at ffff8881243384b8 which belongs to the cache jffs2_xattr_ref of size 48 The buggy address is located 40 bytes inside of 48-byte region [ffff8881243384b8, ffff8881243384e8) [...] ================================================================== The triggering of the BUG is shown in the following stack: ----------------------------------------------------------- jffs2_fill_super jffs2_do_fill_super jffs2_do_mount_fs jffs2_build_filesystem jffs2_scan_medium jffs2_scan_eraseblock <--- ERROR jffs2_clear_xattr_subsystem <--- free jffs2_clear_xattr_subsystem <--- free again ----------------------------------------------------------- An error is returned in jffs2_do_mount_fs(). If the error is returned by jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to be executed. If the error is returned by jffs2_build_filesystem(), the jffs2_clear_xattr_subsystem() also does not need to be executed again. So move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root' to fix this UAF problem. Fixes: aa98d7cf59b5 ("[JFFS2][XATTR] XATTR support on JFFS2 (version. 5)") Cc: stable@vger.kernel.org Reported-by: Hulk Robot Signed-off-by: Baokun Li Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman --- fs/jffs2/fs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/jffs2/fs.c +++ b/fs/jffs2/fs.c @@ -602,8 +602,8 @@ out_root: jffs2_free_ino_caches(c); jffs2_free_raw_node_refs(c); kvfree(c->blocks); - out_inohash: jffs2_clear_xattr_subsystem(c); + out_inohash: kfree(c->inocache_list); out_wbuf: jffs2_flash_cleanup(c);