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 D17C2C432C3 for ; Sat, 16 Nov 2019 14:15:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9AB9720700 for ; Sat, 16 Nov 2019 14:15:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727677AbfKPOPJ (ORCPT ); Sat, 16 Nov 2019 09:15:09 -0500 Received: from mail-io1-f70.google.com ([209.85.166.70]:55958 "EHLO mail-io1-f70.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727672AbfKPOPJ (ORCPT ); Sat, 16 Nov 2019 09:15:09 -0500 Received: by mail-io1-f70.google.com with SMTP id c67so9511527iof.22 for ; Sat, 16 Nov 2019 06:15:08 -0800 (PST) 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:message-id:subject:from:to; bh=r4BpNWbf4xFpW3cj9suOlpyJ+CHQ8j0TEcjFp7mTyoc=; b=oHKV61RYcFg8oZ9pi1QikQABzR3SLbOL0pilQJDO8oteUNLvwRz+qxntjSTmUoG3Bl xU699cBpl8TORSXmD5rmBg/QBuV0Ckx/h/3xQxb32Y63R1Vz8eFf+W2zrMD1vM12QEHc YGdmf4iHmzE54nKdSoP89l4SKuW+vvw3bEYK/YVI96dGyA/jQU0fVUIVvIh3iCggnlG1 syhMdEb3hXZ7ggTae3e94lD1t6nOznDqQoHq7Ky7HAUC8uMAVJBya6pgqmEeNPxulw8e +z3ZxhId3MPaBgAwHNw06+T2FTRSxjZoM92gjwuEoFI8tqVJcORuKlol3j8PQy0CaMLA bl/A== X-Gm-Message-State: APjAAAWYKP6fCbj8Ed4+YBIPzA7zFrm/MX8a6rvL+01bpIfM+tr+TmNI 4M/5zmWpfjYFrkVxC4yzevka8fIWvdE3k/mueNu65EirxXek X-Google-Smtp-Source: APXvYqyC0l37Lcb7JkdxBYMGF3sYIPeYx+diVpPlrKNR2TMovMypf6Ge91HVUDNQdujey7E8zXosuDbnIdQQjaJ4+puzJTay6aeW MIME-Version: 1.0 X-Received: by 2002:a92:8906:: with SMTP id n6mr6606620ild.202.1573913708468; Sat, 16 Nov 2019 06:15:08 -0800 (PST) Date: Sat, 16 Nov 2019 06:15:08 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <0000000000008026b8059777575c@google.com> Subject: possible deadlock in proc_pid_syscall From: syzbot To: adobriyan@gmail.com, akpm@linux-foundation.org, casey@schaufler-ca.com, christian@brauner.io, keescook@chromium.org, 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"; format=flowed; delsp=yes Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: eb70e26c Merge tag 'arm64-fixes' of git://git.kernel.org/p.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10a38772e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=7654f9089a2e8c85 dashboard link: https://syzkaller.appspot.com/bug?extid=ffc5f92d13ebf6b3e760 compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+ffc5f92d13ebf6b3e760@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 5.4.0-rc7+ #0 Not tainted ------------------------------------------------------ syz-executor.4/16763 is trying to acquire lock: ffff8880916fc710 (&sig->cred_guard_mutex){+.+.}, at: lock_trace fs/proc/base.c:406 [inline] ffff8880916fc710 (&sig->cred_guard_mutex){+.+.}, at: proc_pid_syscall+0x66/0x3a0 fs/proc/base.c:635 but task is already holding lock: ffff8880a02001c0 (&p->lock){+.+.}, at: seq_read+0x6e/0xd70 fs/seq_file.c:161 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&p->lock){+.+.}: lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487 __mutex_lock_common+0x14c/0x2e20 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118 seq_read+0x6e/0xd70 fs/seq_file.c:161 proc_reg_read+0x1e2/0x2d0 fs/proc/inode.c:223 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4b1/0x5b0 fs/read_write.c:935 vfs_readv+0xc2/0x120 fs/read_write.c:997 kernel_readv fs/splice.c:359 [inline] default_file_splice_read+0x544/0x8d0 fs/splice.c:414 do_splice_to fs/splice.c:877 [inline] splice_direct_to_actor+0x39c/0xac0 fs/splice.c:954 do_splice_direct+0x200/0x330 fs/splice.c:1063 do_sendfile+0x7e4/0xfd0 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1525 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x176/0x1b0 fs/read_write.c:1511 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (sb_writers#3){.+.+}: lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487 percpu_down_read include/linux/percpu-rwsem.h:40 [inline] __sb_start_write+0xeb/0x430 fs/super.c:1672 sb_start_write include/linux/fs.h:1650 [inline] mnt_want_write+0x4a/0xa0 fs/namespace.c:354 ovl_want_write+0x77/0x80 fs/overlayfs/util.c:21 ovl_create_object+0xaf/0x2d0 fs/overlayfs/dir.c:596 ovl_create+0x29/0x30 fs/overlayfs/dir.c:627 lookup_open fs/namei.c:3224 [inline] do_last fs/namei.c:3314 [inline] path_openat+0x2236/0x4420 fs/namei.c:3525 do_filp_open+0x192/0x3d0 fs/namei.c:3555 do_sys_open+0x29f/0x560 fs/open.c:1097 ksys_open include/linux/syscalls.h:1385 [inline] __do_sys_creat fs/open.c:1155 [inline] __se_sys_creat fs/open.c:1153 [inline] __x64_sys_creat+0x65/0x70 fs/open.c:1153 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (&ovl_i_mutex_dir_key[depth]){++++}: lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487 down_read+0x39/0x50 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] do_last fs/namei.c:3313 [inline] path_openat+0xa9a/0x4420 fs/namei.c:3525 do_filp_open+0x192/0x3d0 fs/namei.c:3555 do_open_execat+0xff/0x610 fs/exec.c:857 __do_execve_file+0x766/0x1cc0 fs/exec.c:1762 do_execveat_common fs/exec.c:1868 [inline] do_execve fs/exec.c:1885 [inline] __do_sys_execve fs/exec.c:1961 [inline] __se_sys_execve fs/exec.c:1956 [inline] __x64_sys_execve+0x94/0xb0 fs/exec.c:1956 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&sig->cred_guard_mutex){+.+.}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain+0x161e/0x7bc0 kernel/locking/lockdep.c:2971 __lock_acquire+0xc75/0x1be0 kernel/locking/lockdep.c:3955 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487 __mutex_lock_common+0x14c/0x2e20 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_killable_nested+0x1b/0x30 kernel/locking/mutex.c:1133 lock_trace fs/proc/base.c:406 [inline] proc_pid_syscall+0x66/0x3a0 fs/proc/base.c:635 proc_single_show+0xd8/0x120 fs/proc/base.c:756 seq_read+0x4cd/0xd70 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4b1/0x5b0 fs/read_write.c:935 vfs_readv fs/read_write.c:997 [inline] do_preadv+0x178/0x290 fs/read_write.c:1089 __do_sys_preadv fs/read_write.c:1139 [inline] __se_sys_preadv fs/read_write.c:1134 [inline] __x64_sys_preadv+0x9e/0xb0 fs/read_write.c:1134 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &sig->cred_guard_mutex --> sb_writers#3 --> &p->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&p->lock); lock(sb_writers#3); lock(&p->lock); lock(&sig->cred_guard_mutex); *** DEADLOCK *** 1 lock held by syz-executor.4/16763: #0: ffff8880a02001c0 (&p->lock){+.+.}, at: seq_read+0x6e/0xd70 fs/seq_file.c:161 stack backtrace: CPU: 0 PID: 16763 Comm: syz-executor.4 Not tainted 5.4.0-rc7+ #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+0x1fb/0x318 lib/dump_stack.c:118 print_circular_bug+0xc2d/0xe60 kernel/locking/lockdep.c:1685 check_noncircular+0x206/0x3a0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain+0x161e/0x7bc0 kernel/locking/lockdep.c:2971 __lock_acquire+0xc75/0x1be0 kernel/locking/lockdep.c:3955 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487 __mutex_lock_common+0x14c/0x2e20 kernel/locking/mutex.c:956 __mutex_lock kernel/locking/mutex.c:1103 [inline] mutex_lock_killable_nested+0x1b/0x30 kernel/locking/mutex.c:1133 lock_trace fs/proc/base.c:406 [inline] proc_pid_syscall+0x66/0x3a0 fs/proc/base.c:635 proc_single_show+0xd8/0x120 fs/proc/base.c:756 seq_read+0x4cd/0xd70 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:714 [inline] do_iter_read+0x4b1/0x5b0 fs/read_write.c:935 vfs_readv fs/read_write.c:997 [inline] do_preadv+0x178/0x290 fs/read_write.c:1089 __do_sys_preadv fs/read_write.c:1139 [inline] __se_sys_preadv fs/read_write.c:1134 [inline] __x64_sys_preadv+0x9e/0xb0 fs/read_write.c:1134 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a669 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff34e552c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a669 RDX: 00000000000001e3 RSI: 00000000200013c0 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff34e5536d4 R13: 00000000004c7ef1 R14: 00000000004dde10 R15: 00000000ffffffff --- This bug 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 syzkaller@googlegroups.com. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.