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=-8.7 required=3.0 tests=BAYES_00,FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 C576DC433E1 for ; Wed, 26 Aug 2020 09:45:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9D172075E for ; Wed, 26 Aug 2020 09:45:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728146AbgHZJpZ (ORCPT ); Wed, 26 Aug 2020 05:45:25 -0400 Received: from mail-io1-f72.google.com ([209.85.166.72]:50969 "EHLO mail-io1-f72.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id 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MIME-Version: 1.0 X-Received: by 2002:a6b:fd13:: with SMTP id c19mr11286158ioi.93.1598435122908; Wed, 26 Aug 2020 02:45:22 -0700 (PDT) Date: Wed, 26 Aug 2020 02:45:22 -0700 In-Reply-To: <0000000000004740cd05ac444126@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000b2941205adc4ad44@google.com> Subject: Re: KASAN: use-after-free Write in afs_manage_cell From: syzbot To: dhowells@redhat.com, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following issue on: HEAD commit: abb3438d Merge tag 'm68knommu-for-v5.9-rc3' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1753522e900000 kernel config: https://syzkaller.appspot.com/x/.config?x=978db74cb30aa994 dashboard link: https://syzkaller.appspot.com/bug?extid=f59c67285cb61166a0cf compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a9888e900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=157cb346900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f59c67285cb61166a0cf@syzkaller.appspotmail.com FS-Cache: N-cookie c=00000000a6a6ef54 [p=000000005b0520e2 fl=2 nc=0 na=1] FS-Cache: N-cookie d=00000000a15022ee n=0000000040eaeaa1 FS-Cache: N-key=[5] '23ee2ea1fb' ================================================================== BUG: KASAN: use-after-free in afs_activate_cell fs/afs/cell.c:609 [inline] BUG: KASAN: use-after-free in afs_manage_cell+0xea0/0x11c0 fs/afs/cell.c:697 Write of size 8 at addr ffff888098036890 by task kworker/0:0/5 CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.9.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: afs afs_manage_cell Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 afs_activate_cell fs/afs/cell.c:609 [inline] afs_manage_cell+0xea0/0x11c0 fs/afs/cell.c:697 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Allocated by task 8859: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461 kmem_cache_alloc_trace+0x16e/0x2c0 mm/slab.c:3550 kmalloc include/linux/slab.h:554 [inline] kzalloc include/linux/slab.h:666 [inline] afs_alloc_cell fs/afs/cell.c:151 [inline] afs_lookup_cell+0x5c8/0x1440 fs/afs/cell.c:262 afs_parse_source fs/afs/super.c:290 [inline] afs_parse_param+0x404/0x8c0 fs/afs/super.c:326 vfs_parse_fs_param fs/fs_context.c:117 [inline] vfs_parse_fs_param+0x203/0x550 fs/fs_context.c:98 vfs_parse_fs_string+0xe6/0x150 fs/fs_context.c:161 generic_parse_monolithic+0x16f/0x1f0 fs/fs_context.c:201 do_new_mount fs/namespace.c:2871 [inline] path_mount+0x133f/0x2070 fs/namespace.c:3192 do_mount fs/namespace.c:3205 [inline] __do_sys_mount fs/namespace.c:3413 [inline] __se_sys_mount fs/namespace.c:3390 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3390 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 3903: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422 __cache_free mm/slab.c:3418 [inline] kfree+0x103/0x2c0 mm/slab.c:3756 rcu_do_batch kernel/rcu/tree.c:2428 [inline] rcu_core+0x5c7/0x1190 kernel/rcu/tree.c:2656 __do_softirq+0x2de/0xa24 kernel/softirq.c:298 Last call_rcu(): kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346 __call_rcu kernel/rcu/tree.c:2894 [inline] call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968 afs_manage_cell+0x250/0x11c0 fs/afs/cell.c:751 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Second to last call_rcu(): kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48 kasan_record_aux_stack+0x82/0xb0 mm/kasan/generic.c:346 __call_rcu kernel/rcu/tree.c:2894 [inline] call_rcu+0x14f/0x7e0 kernel/rcu/tree.c:2968 afs_manage_cell+0x250/0x11c0 fs/afs/cell.c:751 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 The buggy address belongs to the object at ffff888098036800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 144 bytes inside of 1024-byte region [ffff888098036800, ffff888098036c00) The buggy address belongs to the page: page:00000000a84846b4 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x98036 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea000225ef48 ffffea000225e008 ffff8880aa040700 raw: 0000000000000000 ffff888098036000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888098036780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888098036800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888098036880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888098036900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888098036980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================