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=-5.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C978CC5DF62 for ; Wed, 6 Nov 2019 07:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 825B8206A3 for ; Wed, 6 Nov 2019 07:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731351AbfKFH6J (ORCPT ); Wed, 6 Nov 2019 02:58:09 -0500 Received: from mail-io1-f69.google.com ([209.85.166.69]:42150 "EHLO mail-io1-f69.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP 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MIME-Version: 1.0 X-Received: by 2002:a92:d484:: with SMTP id p4mr1352967ilg.52.1573027087769; Tue, 05 Nov 2019 23:58:07 -0800 (PST) Date: Tue, 05 Nov 2019 23:58:07 -0800 In-Reply-To: <0000000000002e4a260576c1589d@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000c9eaf30596a8e8a5@google.com> Subject: Re: KASAN: use-after-free Read in relay_switch_subbuf From: syzbot To: akpm@linux-foundation.org, ebiggers@google.com, gregkh@linuxfoundation.org, jannh@google.com, jrdr.linux@gmail.com, keescook@chromium.org, linux-kernel@vger.kernel.org, mawilcox@microsoft.com, rientjes@google.com, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes 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 crash on: HEAD commit: 26bc6721 Merge tag 'for-linus-2019-11-05' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17b7b7cce00000 kernel config: https://syzkaller.appspot.com/x/.config?x=8c5e2eca3f31f9bf dashboard link: https://syzkaller.appspot.com/bug?extid=29093015c21333d1c46d compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=132afbcce00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=179a1f8ae00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+29093015c21333d1c46d@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755 Read of size 8 at addr ffff88808d5054f8 by task kworker/1:3/3760 CPU: 1 PID: 3760 Comm: kworker/1:3 Not tainted 5.4.0-rc6+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events __blk_release_queue Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:634 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755 relay_flush kernel/relay.c:883 [inline] relay_flush+0x1c4/0x280 kernel/relay.c:867 __blk_trace_startstop.isra.0+0x216/0x630 kernel/trace/blktrace.c:662 blk_trace_shutdown+0x5f/0x90 kernel/trace/blktrace.c:746 __blk_release_queue+0x219/0x380 block/blk-sysfs.c:904 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 worker_thread+0x98/0xe40 kernel/workqueue.c:2415 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 11279: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:510 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:518 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc mm/slab.c:3319 [inline] kmem_cache_alloc+0x121/0x710 mm/slab.c:3483 __d_alloc+0x2e/0x8c0 fs/dcache.c:1688 d_alloc+0x4d/0x280 fs/dcache.c:1767 d_alloc_parallel+0xf4/0x1c30 fs/dcache.c:2519 __lookup_slow+0x1ab/0x500 fs/namei.c:1646 lookup_one_len+0x16d/0x1a0 fs/namei.c:2533 start_creating+0xc5/0x1d0 fs/debugfs/inode.c:339 __debugfs_create_file+0x65/0x3f0 fs/debugfs/inode.c:384 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:441 blk_create_buf_file_callback+0x33/0x40 kernel/trace/blktrace.c:444 relay_create_buf_file+0xf9/0x180 kernel/relay.c:428 relay_open_buf.part.0+0x76e/0xb60 kernel/relay.c:457 relay_open_buf kernel/relay.c:449 [inline] relay_open kernel/relay.c:599 [inline] relay_open+0x523/0x980 kernel/relay.c:563 do_blk_trace_setup+0x3f0/0xb50 kernel/trace/blktrace.c:526 __blk_trace_setup+0xe3/0x190 kernel/trace/blktrace.c:571 blk_trace_ioctl+0x170/0x300 kernel/trace/blktrace.c:710 blkdev_ioctl+0x126/0x1c20 block/ioctl.c:592 block_ioctl+0xee/0x130 fs/block_dev.c:1954 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 11303: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] kasan_set_free_info mm/kasan/common.c:332 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480 __cache_free mm/slab.c:3425 [inline] kmem_cache_free+0x86/0x320 mm/slab.c:3693 __d_free+0x20/0x30 fs/dcache.c:271 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2157 [inline] rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386 __do_softirq+0x262/0x98c kernel/softirq.c:292 The buggy address belongs to the object at ffff88808d5054a0 which belongs to the cache dentry of size 288 The buggy address is located 88 bytes inside of 288-byte region [ffff88808d5054a0, ffff88808d5055c0) The buggy address belongs to the page: page:ffffea0002354140 refcount:1 mapcount:0 mapping:ffff8880aa57b000 index:0xffff88808d505e40 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea000299b6c8 ffffea0002353f08 ffff8880aa57b000 raw: ffff88808d505e40 ffff88808d505080 0000000100000009 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808d505380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808d505400: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > ffff88808d505480: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808d505500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808d505580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================