[syzbot] [reiserfs?] possible deadlock in chmod_common (2)

* [syzbot] [reiserfs?] possible deadlock in chmod_common (2)
@ 2023-11-10 12:38 syzbot
  2023-12-21  4:05 ` syzbot
  2023-12-22  3:06 ` [syzbot] [reiserfs?] possible deadlock in chmod_common (2) syzbot
  0 siblings, 2 replies; 4+ messages in thread
From: syzbot @ 2023-11-10 12:38 UTC (permalink / raw)
  To: linux-fsdevel, linux-kernel, reiserfs-devel, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    8de1e7afcc1c Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=136e2560e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3e6feaeda5dcbc27
dashboard link: https://syzkaller.appspot.com/bug?extid=83693dbba860b4f2e549
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0f00907f9764/disk-8de1e7af.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0502fe78c60d/vmlinux-8de1e7af.xz
kernel image: https://storage.googleapis.com/syzbot-assets/192135168cc0/Image-8de1e7af.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+83693dbba860b4f2e549@syzkaller.appspotmail.com

REISERFS (device loop5): Using tea hash to sort names
REISERFS (device loop5): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc7-syzkaller-g8de1e7afcc1c #0 Not tainted
------------------------------------------------------
syz-executor.5/10863 is trying to acquire lock:
ffff00012f979d60 (&type->i_mutex_dir_key#18){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
ffff00012f979d60 (&type->i_mutex_dir_key#18){+.+.}-{3:3}, at: chmod_common+0x17c/0x418 fs/open.c:637

but task is already holding lock:
ffff00012d90a410 (sb_writers#26){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:403

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#26){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1571 [inline]
       sb_start_write+0x60/0x2ec include/linux/fs.h:1646
       mnt_want_write_file+0x64/0x1e8 fs/namespace.c:447
       reiserfs_ioctl+0x188/0x42c fs/reiserfs/ioctl.c:103
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
       __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
       el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

-> #1 (&sbi->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799
       reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
       reiserfs_lookup+0x128/0x45c fs/reiserfs/namei.c:364
       __lookup_slow+0x250/0x374 fs/namei.c:1694
       lookup_one_len+0x178/0x28c fs/namei.c:2746
       reiserfs_lookup_privroot+0x8c/0x184 fs/reiserfs/xattr.c:977
       reiserfs_fill_super+0x1bc0/0x2028 fs/reiserfs/super.c:2174
       mount_bdev+0x1e8/0x2b4 fs/super.c:1629
       get_super_block+0x44/0x58 fs/reiserfs/super.c:2601
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:662
       vfs_get_tree+0x90/0x288 fs/super.c:1750
       do_new_mount+0x25c/0x8c8 fs/namespace.c:3335
       path_mount+0x590/0xe04 fs/namespace.c:3662
       do_mount fs/namespace.c:3675 [inline]
       __do_sys_mount fs/namespace.c:3884 [inline]
       __se_sys_mount fs/namespace.c:3861 [inline]
       __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3861
       __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
       el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

-> #0 (&type->i_mutex_dir_key#18){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
       lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
       down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
       inode_lock include/linux/fs.h:802 [inline]
       chmod_common+0x17c/0x418 fs/open.c:637
       vfs_fchmod fs/open.c:659 [inline]
       __do_sys_fchmod fs/open.c:668 [inline]
       __se_sys_fchmod fs/open.c:662 [inline]
       __arm64_sys_fchmod+0xe0/0x150 fs/open.c:662
       __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
       el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#18 --> &sbi->lock --> sb_writers#26

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_writers#26);
                               lock(&sbi->lock);
                               lock(sb_writers#26);
  lock(&type->i_mutex_dir_key#18);

 *** DEADLOCK ***

1 lock held by syz-executor.5/10863:
 #0: ffff00012d90a410 (sb_writers#26){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:403

stack backtrace:
CPU: 1 PID: 10863 Comm: syz-executor.5 Not tainted 6.6.0-rc7-syzkaller-g8de1e7afcc1c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3868 [inline]
 __lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:802 [inline]
 chmod_common+0x17c/0x418 fs/open.c:637
 vfs_fchmod fs/open.c:659 [inline]
 __do_sys_fchmod fs/open.c:668 [inline]
 __se_sys_fchmod fs/open.c:662 [inline]
 __arm64_sys_fchmod+0xe0/0x150 fs/open.c:662
 __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
 el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
netlink: 12 bytes leftover after parsing attributes in process `syz-executor.5'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor.5'.

---
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