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=-4.9 required=3.0 tests=DATE_IN_PAST_12_24, FROM_LOCAL_HEX,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 987A5C282DA for ; Fri, 19 Apr 2019 18:56:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 638D920663 for ; Fri, 19 Apr 2019 18:56:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727216AbfDSS4X (ORCPT ); Fri, 19 Apr 2019 14:56:23 -0400 Received: from mail-io1-f69.google.com ([209.85.166.69]:46485 "EHLO mail-io1-f69.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726164AbfDSS4X (ORCPT ); Fri, 19 Apr 2019 14:56:23 -0400 Received: by mail-io1-f69.google.com with SMTP id i84so1543479iof.13 for ; Fri, 19 Apr 2019 11:56:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:in-reply-to:message-id:subject :from:to; bh=SjY449fhMaQ7ERvE3A+f6DfzGfay+dUg6pdjzIryT+s=; b=JFK+sM3S7Oo7LOCnyy8zXkXv5exFlGqynxIPOeIJX5nuL3oYI+KTzj6uMlXZAz053B Cc2IrBvMpP8HPSpDsTUY6CNjSZQS+UGznVFo0QNxYa3fe+Ro2afAmY78frWbkaDDs6mM 3meHVYfUDFovZgwwxGuRDis7NFuts6vDSBbGc1da8uzncVtlQuWSFiVBA5OY51qxNq2K zExJaSiFHGXP6yB72ViomlJ8TGj/iA8l0sRlV3teR46r3KOg9OrXjquylU2ZG7QUjfU1 Tw18xBeZf9et366j86xgtxkX6vGgH6hObwTFeJcDao5byJQg7ekbxKlgClzTm4fam5hv mEYg== X-Gm-Message-State: APjAAAXbk6ytW1fGweGbXAJfcs4OssvS8yJJ6cb6BCcP0ozm6kCBZ+Uj bkzbcti5xSJv7VLRz8HLC1gD1DpfPLTdW2SiUh/laUwKgr6+ X-Google-Smtp-Source: APXvYqwnkK1AqehEgQWQ8sef2VtIx+ZRTnz1SJhosMj/bO2/3xwzzqWLL9kt96w95OGBcNka086G6KqOEQQIpi9bDi86+M8g93ZD MIME-Version: 1.0 X-Received: by 2002:a6b:db19:: with SMTP id t25mr1554070ioc.140.1555651864760; Thu, 18 Apr 2019 22:31:04 -0700 (PDT) Date: Thu, 18 Apr 2019 22:31:04 -0700 In-Reply-To: <00000000000044cbf80576baaecd@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000cb1d0d0586db6c4c@google.com> Subject: Re: possible deadlock in path_openat From: syzbot To: amir73il@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes 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: 6d906f99 Merge tag 'arm64-fixes' of git://git.kernel.org/p.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10917b8f200000 kernel config: https://syzkaller.appspot.com/x/.config?x=856fc6d0fbbeede9 dashboard link: https://syzkaller.appspot.com/bug?extid=a55ccfc8a853d3cff213 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101767b7200000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13c15013200000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a55ccfc8a853d3cff213@syzkaller.appspotmail.com overlayfs: workdir and upperdir must reside under the same mount ====================================================== WARNING: possible circular locking dependency detected 5.1.0-rc5+ #74 Not tainted ------------------------------------------------------ syz-executor949/9348 is trying to acquire lock: 000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: inode_lock_shared include/linux/fs.h:782 [inline] 000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: do_last fs/namei.c:3321 [inline] 000000005d993096 (&ovl_i_mutex_dir_key[depth]#2){++++}, at: path_openat+0x1e98/0x46e0 fs/namei.c:3533 but task is already holding lock: 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline] 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&sig->cred_guard_mutex){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102 do_io_accounting+0x1f4/0x830 fs/proc/base.c:2740 proc_tgid_io_accounting+0x23/0x30 fs/proc/base.c:2789 proc_single_show+0xf6/0x170 fs/proc/base.c:744 seq_read+0x4db/0x1130 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:922 vfs_readv+0xf0/0x160 fs/read_write.c:984 kernel_readv fs/splice.c:358 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:413 do_splice_to+0x12a/0x190 fs/splice.c:876 splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953 do_splice_direct+0x1da/0x2a0 fs/splice.c:1062 do_sendfile+0x597/0xd00 fs/read_write.c:1443 __do_sys_sendfile64 fs/read_write.c:1504 [inline] __se_sys_sendfile64 fs/read_write.c:1490 [inline] __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1490 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #3 (&p->lock){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 seq_read+0x71/0x1130 fs/seq_file.c:161 proc_reg_read+0x1fe/0x2c0 fs/proc/inode.c:227 do_loop_readv_writev fs/read_write.c:701 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_read+0x4a9/0x660 fs/read_write.c:922 vfs_readv+0xf0/0x160 fs/read_write.c:984 kernel_readv fs/splice.c:358 [inline] default_file_splice_read+0x475/0x890 fs/splice.c:413 do_splice_to+0x12a/0x190 fs/splice.c:876 do_splice+0x110b/0x1420 fs/splice.c:1183 __do_sys_splice fs/splice.c:1424 [inline] __se_sys_splice fs/splice.c:1404 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1404 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&pipe->mutex/1){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 pipe_lock_nested fs/pipe.c:62 [inline] pipe_lock+0x6e/0x80 fs/pipe.c:70 iter_file_splice_write+0x18b/0xbe0 fs/splice.c:696 do_splice_from fs/splice.c:847 [inline] do_splice+0x70a/0x1420 fs/splice.c:1154 __do_sys_splice fs/splice.c:1424 [inline] __se_sys_splice fs/splice.c:1404 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1404 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#6){.+.+}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 percpu_down_read include/linux/percpu-rwsem.h:36 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1621 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_do_remove+0xe9/0xd70 fs/overlayfs/dir.c:840 ovl_rmdir+0x1b/0x20 fs/overlayfs/dir.c:890 vfs_rmdir fs/namei.c:3878 [inline] vfs_rmdir+0x19c/0x470 fs/namei.c:3857 do_rmdir+0x39e/0x420 fs/namei.c:3939 __do_sys_rmdir fs/namei.c:3957 [inline] __se_sys_rmdir fs/namei.c:3955 [inline] __x64_sys_rmdir+0x36/0x40 fs/namei.c:3955 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_dir_key[depth]#2){++++}: check_prevs_add kernel/locking/lockdep.c:2333 [inline] validate_chain kernel/locking/lockdep.c:2714 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 down_read+0x3b/0x90 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:782 [inline] do_last fs/namei.c:3321 [inline] path_openat+0x1e98/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_open_execat+0x137/0x690 fs/exec.c:856 __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 do_execveat_common fs/exec.c:1865 [inline] do_execve fs/exec.c:1882 [inline] __do_sys_execve fs/exec.c:1958 [inline] __se_sys_execve fs/exec.c:1953 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:1953 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_dir_key[depth]#2 --> &p->lock --> &sig->cred_guard_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sig->cred_guard_mutex); lock(&p->lock); lock(&sig->cred_guard_mutex); lock(&ovl_i_mutex_dir_key[depth]#2); *** DEADLOCK *** 1 lock held by syz-executor949/9348: #0: 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds fs/exec.c:1407 [inline] #0: 00000000ef248b1d (&sig->cred_guard_mutex){+.+.}, at: __do_execve_file.isra.0+0x376/0x23f0 fs/exec.c:1750 stack backtrace: CPU: 1 PID: 9348 Comm: syz-executor949 Not tainted 5.1.0-rc5+ #74 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+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1571 check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2220 check_prevs_add kernel/locking/lockdep.c:2333 [inline] validate_chain kernel/locking/lockdep.c:2714 [inline] __lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3701 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 down_read+0x3b/0x90 kernel/locking/rwsem.c:24 inode_lock_shared include/linux/fs.h:782 [inline] do_last fs/namei.c:3321 [inline] path_openat+0x1e98/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_open_execat+0x137/0x690 fs/exec.c:856 __do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758 do_execveat_common fs/exec.c:1865 [inline] do_execve fs/exec.c:1882 [inline] __do_sys_execve fs/exec.c:1958 [inline] __se_sys_execve fs/exec.c:1953 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:1953 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x447169 Code: e8 4c bb 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 bb 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe4c6a6bdb8 EFLAGS: 00000246 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 00000000006dcc68 RCX: 0000000000447169 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000 RBP: 00000000006dcc60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc6c R13: 00007ffd5a5cb62f R14: 00007fe4c6a6c9c0 R15: 0000000000000000