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 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 409D9C0044D for ; Mon, 16 Mar 2020 07:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1924A20663 for ; Mon, 16 Mar 2020 07:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729674AbgCPH0O (ORCPT ); Mon, 16 Mar 2020 03:26:14 -0400 Received: from mail-io1-f71.google.com ([209.85.166.71]:43439 "EHLO mail-io1-f71.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:e70d:: with SMTP id b13mr21641021ioh.91.1584343572869; Mon, 16 Mar 2020 00:26:12 -0700 (PDT) Date: Mon, 16 Mar 2020 00:26:12 -0700 In-Reply-To: <0000000000002ef1120597b1bc92@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000dcf6ef05a0f3bb1b@google.com> Subject: Re: possible deadlock in lock_trace (3) From: syzbot To: adobriyan@gmail.com, akpm@linux-foundation.org, avagin@gmail.com, casey@schaufler-ca.com, christian@brauner.io, guro@fb.com, kent.overstreet@gmail.com, khlebnikov@yandex-team.ru, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mhocko@suse.com, shakeelb@google.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: a42a7bb6 Merge tag 'irq-urgent-2020-03-15' of git://git.ke.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1237321de00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c2e311dba9a02ba9 dashboard link: https://syzkaller.appspot.com/bug?extid=985c8a3c7f3668d31a49 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1185f753e00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+985c8a3c7f3668d31a49@syzkaller.appspotmail.com overlayfs: './file0' not a directory ====================================================== WARNING: possible circular locking dependency detected 5.6.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.3/11170 is trying to acquire lock: ffff888097db9c50 (&sig->cred_guard_mutex){+.+.}, at: lock_trace+0x45/0xe0 fs/proc/base.c:408 but task is already holding lock: ffff8880913eebe0 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 seq_read+0x6b/0x1160 fs/seq_file.c:161 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x47f/0x650 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x4fb/0xa20 fs/splice.c:422 do_splice_to+0x10e/0x160 fs/splice.c:892 splice_direct_to_actor+0x307/0x980 fs/splice.c:971 do_splice_direct+0x1a8/0x270 fs/splice.c:1080 do_sendfile+0x549/0xc40 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1567 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#4){.+.+}: percpu_down_read include/linux/percpu-rwsem.h:40 [inline] __sb_start_write+0x21b/0x430 fs/super.c:1674 sb_start_write include/linux/fs.h:1650 [inline] mnt_want_write+0x3a/0xb0 fs/namespace.c:354 ovl_setattr+0xdd/0x8b0 fs/overlayfs/inode.c:27 notify_change+0xb6d/0x1060 fs/attr.c:336 do_truncate+0x134/0x1f0 fs/open.c:64 handle_truncate fs/namei.c:3083 [inline] do_last fs/namei.c:3496 [inline] path_openat+0x291f/0x32b0 fs/namei.c:3607 do_filp_open+0x192/0x260 fs/namei.c:3637 do_sys_openat2+0x54c/0x740 fs/open.c:1146 do_sys_open+0xc3/0x140 fs/open.c:1162 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_key[depth]){+.+.}: down_write+0x8d/0x150 kernel/locking/rwsem.c:1534 inode_lock include/linux/fs.h:792 [inline] process_measurement+0x68a/0x1740 security/integrity/ima/ima_main.c:230 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:442 do_last fs/namei.c:3494 [inline] path_openat+0x127f/0x32b0 fs/namei.c:3607 do_filp_open+0x192/0x260 fs/namei.c:3637 do_open_execat+0x122/0x600 fs/exec.c:860 __do_execve_file.isra.0+0x16d5/0x2270 fs/exec.c:1765 do_execveat_common fs/exec.c:1871 [inline] do_execve fs/exec.c:1888 [inline] __do_sys_execve fs/exec.c:1964 [inline] __se_sys_execve fs/exec.c:1959 [inline] __x64_sys_execve+0x8a/0xb0 fs/exec.c:1959 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x201b/0x3ca0 kernel/locking/lockdep.c:3954 lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 lock_trace+0x45/0xe0 fs/proc/base.c:408 proc_pid_personality+0x17/0xc0 fs/proc/base.c:3052 proc_single_show+0xf7/0x1c0 fs/proc/base.c:758 seq_read+0x4b9/0x1160 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_loop_readv_writev fs/read_write.c:701 [inline] do_iter_read+0x47f/0x650 fs/read_write.c:935 vfs_readv+0xf0/0x160 fs/read_write.c:1053 kernel_readv fs/splice.c:365 [inline] default_file_splice_read+0x4fb/0xa20 fs/splice.c:422 do_splice_to+0x10e/0x160 fs/splice.c:892 splice_direct_to_actor+0x307/0x980 fs/splice.c:971 do_splice_direct+0x1a8/0x270 fs/splice.c:1080 do_sendfile+0x549/0xc40 fs/read_write.c:1520 __do_sys_sendfile64 fs/read_write.c:1581 [inline] __se_sys_sendfile64 fs/read_write.c:1567 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1567 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#4 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#4); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 2 locks held by syz-executor.3/11170: #0: ffff88809fa24428 (sb_writers#13){.+.+}, at: file_start_write include/linux/fs.h:2904 [inline] #0: ffff88809fa24428 (sb_writers#13){.+.+}, at: do_sendfile+0x939/0xc40 fs/read_write.c:1519 #1: ffff8880913eebe0 (&p->lock){+.+.}, at: seq_read+0x6b/0x1160 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 11170 Comm: syz-executor.3 Not tainted 5.6.0-rc5-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+0x188/0x20d lib/dump_stack.c:118 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1808 check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x201b/0x3ca0 kernel/locking/lockdep.c:3954 lock_acqu