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=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 06238C433E7 for ; Wed, 14 Oct 2020 08:29:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E91B221EB for ; Wed, 14 Oct 2020 08:29:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tDmwgwNS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729232AbgJNI3m (ORCPT ); Wed, 14 Oct 2020 04:29:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727658AbgJNI3d (ORCPT ); Wed, 14 Oct 2020 04:29:33 -0400 Received: from mail-pl1-x643.google.com (mail-pl1-x643.google.com [IPv6:2607:f8b0:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67A4DC051125 for ; Wed, 14 Oct 2020 00:52:21 -0700 (PDT) Received: by mail-pl1-x643.google.com with SMTP id d23so1329335pll.7 for ; Wed, 14 Oct 2020 00:52:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:subject:cc:from:in-reply-to:message-id:date:user-agent :mime-version:content-language:content-transfer-encoding; bh=8dTw1vdHe05pw7PwZ6jgowSrJqqbe0weLTZIFqcmFiI=; b=tDmwgwNSsEMcpJim7gwfRmCEiX3G9cYDSv3OTAKxhVvsmJEE1WP3V1aYgRvPm7l7PB DYNgS4j6iuuXyvxtkCitKl5gr67+dQzJdjrr5wLF3Nc0Q+NTdCjjcVT8+odz8U9uBmGJ icwB1TkhzfMxxlMyy0N6jm2B/JzMvLLzXI1pl4bfanA6y5wVXQPxAOg05Tvh0NPZPJ14 i4ajrPWTCD3PWUVKwUuUieY21t2VouzvJFlDdqlAMoGlPOv0STprVen80DPUGVyPyy3N z3gN4HC6n3tkcDd5xlN5u0MRa+GvtEzlSirkTPm3Ra77XL4fDqNGV+I+W7v+FataJs0C yRpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:subject:cc:from:in-reply-to:message-id:date :user-agent:mime-version:content-language:content-transfer-encoding; bh=8dTw1vdHe05pw7PwZ6jgowSrJqqbe0weLTZIFqcmFiI=; b=R6f83/Z5PcboirqtymCt7k9Vl/Cc1fUI43QU01C3eEgcyilpXPA8rG6aOsyv4xMbAs BNQiU+QwbAdTKqgf/7DhHuNsegUVy6IUMShjqogCpcLZ7Us1AobTQMLTvgPih5hsflob C1+IfRseRHBvd9OKY96eW2DkEALOvoAePgF/spZWAsM3ldRJMaSkYm2s+ln7bMgtyIqs bmqxTql/SPf5p4KDZz1VnKillwl64FY+oLa8+YPN5T0jA+WM0Gyzjs83pR+TQQslrfZ9 NOdcm7vaIAALXzMFftQyqAM7aNjHfL02Xs+DsZXC90ASyLhFRjTThGo07gzngPqCzWi0 qBEQ== X-Gm-Message-State: AOAM533rXGOq1dqBG+D5cq2uvgwQudkG9InNwzuuI99GWpCptpDOWKAc OMXXe0nnh9ODKPlosPRcBmXq/7z0mYNniw== X-Google-Smtp-Source: ABdhPJxaSQeVs6ZWyYu2mb8WLo8H+b0T7fe/8bQho7I9qGEwHL4QEv5BAvtmwp5nVeMGELbiNteclA== X-Received: by 2002:a17:90a:b287:: with SMTP id c7mr2334114pjr.141.1602661940853; Wed, 14 Oct 2020 00:52:20 -0700 (PDT) Received: from fox-laptop.local ([162.216.240.138]) by smtp.gmail.com with ESMTPSA id k127sm2241140pgk.10.2020.10.14.00.52.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Oct 2020 00:52:20 -0700 (PDT) To: phillip@squashfs.org.uk, syzkaller-bugs@googlegroups.com Subject: Re: KASAN: slab-out-of-bounds Read in squashfs_get_id Cc: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org From: Fox Chen In-Reply-To: <0000000000002954fa05b02468d7@google.com> Message-ID: Date: Wed, 14 Oct 2020 15:52:12 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I found this bug was caused by either uid/gid info in superblocks or id_index_table is corrupted. The uid/gid index is larger than the size of msblk->id_table. Should I add a sanity check to squashfs_get_id?? The complete solution is to record the size of msblk->id_table in msblk and check uid/gid index each time in squashfs_get_id. However, this requires a change to msblk struct. A simple solution is to calculate the max available room for uid/gid table by doing msblk->xattr_table - msblk->id_table[0] and check if index is larger than this. While this provides some sort of check, it is imperfect because id_table can be smaller than that. Both of them work out for this bug. thanks, fox On Friday, September 25, 2020 at 10:48:18 PM UTC+8 syzbot wrote: Hello, syzbot found the following issue on: HEAD commit: 171d4ff7 Merge tag 'mmc-v5.9-rc4-2' of git://git.kernel.or.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1597ead3900000 kernel config: https://syzkaller.appspot.com/x/.config?x=af502ec9a451c9fc dashboard link: https://syzkaller.appspot.com/bug?extid=8e28bba73ed1772a6802 compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=172ff481900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17c3e6c5900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8e28bb...@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-out-of-bounds in squashfs_get_id+0xb9/0x1c0 fs/squashfs/id.c:38 Read of size 8 at addr ffff8880a9684b98 by task syz-executor329/6836 CPU: 1 PID: 6836 Comm: syz-executor329 Not tainted 5.9.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d6/0x29e lib/dump_stack.c:118 print_address_description+0x66/0x620 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report+0x132/0x1d0 mm/kasan/report.c:530 squashfs_get_id+0xb9/0x1c0 fs/squashfs/id.c:38 squashfs_new_inode fs/squashfs/inode.c:51 [inline] squashfs_read_inode+0x155/0x2170 fs/squashfs/inode.c:120 squashfs_fill_super+0x1478/0x1790 fs/squashfs/super.c:310 get_tree_bdev+0x3e9/0x5f0 fs/super.c:1342 vfs_get_tree+0x88/0x270 fs/super.c:1547 do_new_mount fs/namespace.c:2875 [inline] path_mount+0x179d/0x29e0 fs/namespace.c:3192 do_mount fs/namespace.c:3205 [inline] __do_sys_mount fs/namespace.c:3413 [inline] __se_sys_mount+0x126/0x180 fs/namespace.c:3390 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x446d1a Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 fd ad fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 da ad fb ff c3 66 0f 1f 84 00 00 00 00 00 RSP: 002b:00007ffd7dd4f8b8 EFLAGS: 00000293 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007ffd7dd4f910 RCX: 0000000000446d1a RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffd7dd4f8d0 RBP: 00007ffd7dd4f8d0 R08: 00007ffd7dd4f910 R09: 00007ffd00000015 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001 R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003 Allocated by task 3913: kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461 kmalloc_node include/linux/slab.h:577 [inline] __vmalloc_area_node mm/vmalloc.c:2429 [inline] __vmalloc_node_range+0x2c7/0x870 mm/vmalloc.c:2511 module_alloc+0x7e/0x90 arch/x86/kernel/module.c:75 bpf_jit_binary_alloc+0x123/0x230 kernel/bpf/core.c:871 bpf_int_jit_compile+0x7995/0x8920 arch/x86/net/bpf_jit_comp.c:1911 bpf_prog_select_runtime+0x76d/0xa60 kernel/bpf/core.c:1807 bpf_migrate_filter net/core/filter.c:1290 [inline] bpf_prepare_filter+0xec2/0x1140 net/core/filter.c:1338 bpf_prog_create_from_user+0x2ad/0x3e0 net/core/filter.c:1432 seccomp_prepare_filter kernel/seccomp.c:567 [inline] seccomp_prepare_user_filter kernel/seccomp.c:604 [inline] seccomp_set_mode_filter kernel/seccomp.c:1546 [inline] do_seccomp+0x852/0x20b0 kernel/seccomp.c:1661 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff8880a9684b80 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 24 bytes inside of 32-byte region [ffff8880a9684b80, ffff8880a9684ba0) The buggy address belongs to the page: page:00000000f697ca3d refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a9684fc1 pfn:0xa9684 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0002a5d5c8 ffffea0002a98588 ffff8880aa440100 raw: ffff8880a9684fc1 ffff8880a9684000 000000010000003f 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a9684a80: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc ffff8880a9684b00: 00 fc fc fc fc fc fc fc fa fb fb fb fc fc fc fc >ffff8880a9684b80: 00 fc fc fc fc fc fc fc fa fb fb fb fc fc fc fc ^ ffff8880a9684c00: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc ffff8880a9684c80: 00 00 01 fc fc fc fc fc fa fb fb fb fc fc fc fc ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzk...@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches