syzbot


WARNING: locking bug in ext4_xattr_inode_update_ref

Status: fixed on 2023/07/01 16:05
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+d4b971e744b1f5439336@syzkaller.appspotmail.com
Fix commit: b928dfdcb27d ext4: set lockdep subclass for the ea_inode in ext4_xattr_inode_cache_find()
First crash: 498d, last: 367d
Cause bisection: failed (error log, bisect log)
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH 0/4] ext4: clean up ea_inode handling 5 (5) 2023/05/24 03:49
[syzbot] [ext4?] WARNING: locking bug in ext4_xattr_inode_update_ref 0 (1) 2023/01/12 00:36
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 WARNING: locking bug in ext4_xattr_inode_update_ref ext4 C error 2 480d 484d 0/1 upstream: reported C repro on 2023/01/21 20:53
linux-4.14 WARNING: locking bug in ext4_xattr_inode_update_ref ext4 C 2 453d 489d 0/1 upstream: reported C repro on 2023/01/16 15:56
upstream WARNING: locking bug in ext4_xattr_inode_update_ref (3) ext4 C 2 5d18h 38d 0/26 upstream: reported C repro on 2024/04/11 09:48
upstream WARNING: locking bug in ext4_xattr_inode_update_ref (2) ext4 syz 1 298d 294d 0/26 auto-obsoleted due to no activity on 2023/09/25 03:27
Last patch testing requests (3)
Created Duration User Patch Repo Result
2023/05/23 03:43 35m tytso@mit.edu git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git test OK log
2023/05/22 21:15 23m tytso@mit.edu git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git test report log
2023/04/18 00:40 15m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log

Sample crash report:
------------[ cut here ]------------
Looking for class "&ea_inode->i_rwsem" with key ext4_fs_type, but found a different class "&sb->s_type->i_mutex_key" with the same key
WARNING: CPU: 1 PID: 13299 at kernel/locking/lockdep.c:941 look_up_lock_class+0xec/0x158 kernel/locking/lockdep.c:938
Modules linked in:
CPU: 1 PID: 13299 Comm: syz-executor369 Not tainted 6.3.0-rc7-syzkaller-g14f8db1c0f9a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : look_up_lock_class+0xec/0x158 kernel/locking/lockdep.c:938
lr : look_up_lock_class+0xec/0x158 kernel/locking/lockdep.c:938
sp : ffff800022556920
x29: ffff800022556920 x28: dfff800000000000 x27: ffff800008f50df0
x26: ffff80001a0a7600 x25: ffff80001a0a7000 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000000 x21: ffff8000160dae58
x20: ffff0000e6c5de48 x19: ffff800018ce3500 x18: 1ffff000044aad7c
x17: 0000000000000000 x16: ffff80001236e294 x15: 0000000000000002
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000001
x11: 0000000000000000 x10: 0000000000000000 x9 : 7a6e2744c5c8a300
x8 : 7a6e2744c5c8a300 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800022556218 x4 : ffff800015e4ccc0 x3 : ffff800008584230
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000
Call trace:
 look_up_lock_class+0xec/0x158 kernel/locking/lockdep.c:938
 register_lock_class+0x8c/0x6a4 kernel/locking/lockdep.c:1290
 __lock_acquire+0x184/0x764c kernel/locking/lockdep.c:4935
 lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:758 [inline]
 ext4_xattr_inode_update_ref+0xac/0x4e0 fs/ext4/xattr.c:1059
 ext4_xattr_inode_inc_ref fs/ext4/xattr.c:1105 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1597 [inline]
 ext4_xattr_set_entry+0x243c/0x2c3c fs/ext4/xattr.c:1737
 ext4_xattr_block_set+0x8e0/0x2cc4 fs/ext4/xattr.c:2043
 ext4_xattr_set_handle+0xb2c/0x12d8 fs/ext4/xattr.c:2458
 ext4_xattr_set+0x1e0/0x354 fs/ext4/xattr.c:2560
 ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
 __vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
 __vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
 vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
 do_setxattr fs/xattr.c:609 [inline]
 setxattr+0x208/0x29c fs/xattr.c:632
 path_setxattr+0x17c/0x258 fs/xattr.c:651
 __do_sys_setxattr fs/xattr.c:667 [inline]
 __se_sys_setxattr fs/xattr.c:663 [inline]
 __arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591
irq event stamp: 287
hardirqs last  enabled at (287): [<ffff80000896749c>] kasan_quarantine_put+0x1a0/0x1c8 mm/kasan/quarantine.c:242
hardirqs last disabled at (286): [<ffff800008967334>] kasan_quarantine_put+0x38/0x1c8 mm/kasan/quarantine.c:215
softirqs last  enabled at (210): [<ffff800008020c1c>] softirq_handle_end kernel/softirq.c:414 [inline]
softirqs last  enabled at (210): [<ffff800008020c1c>] __do_softirq+0xac0/0xd54 kernel/softirq.c:600
softirqs last disabled at (197): [<ffff80000802a658>] ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
---[ end trace 0000000000000000 ]---

============================================
WARNING: possible recursive locking detected
6.3.0-rc7-syzkaller-g14f8db1c0f9a #0 Tainted: G        W         
--------------------------------------------
syz-executor369/13299 is trying to acquire lock:
ffff0000e6c5de48 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff0000e6c5de48 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_xattr_inode_update_ref+0xac/0x4e0 fs/ext4/xattr.c:1059

but task is already holding lock:
ffff0000e6d00400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
ffff0000e6d00400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x17c/0x344 fs/xattr.c:323

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sb->s_type->i_mutex_key#8);
  lock(&sb->s_type->i_mutex_key#8);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor369/13299:
 #0: ffff0000d7938460 (sb_writers#3){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:394
 #1: ffff0000e6d00400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff0000e6d00400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x17c/0x344 fs/xattr.c:323
 #2: ffff0000e6d000c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff0000e6d000c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x1e0/0x12d8 fs/ext4/xattr.c:2373

stack backtrace:
CPU: 1 PID: 13299 Comm: syz-executor369 Tainted: G        W          6.3.0-rc7-syzkaller-g14f8db1c0f9a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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
 __lock_acquire+0x6310/0x764c kernel/locking/lockdep.c:5056
 lock_acquire+0x238/0x718 kernel/locking/lockdep.c:5669
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1573
 inode_lock include/linux/fs.h:758 [inline]
 ext4_xattr_inode_update_ref+0xac/0x4e0 fs/ext4/xattr.c:1059
 ext4_xattr_inode_inc_ref fs/ext4/xattr.c:1105 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1597 [inline]
 ext4_xattr_set_entry+0x243c/0x2c3c fs/ext4/xattr.c:1737
 ext4_xattr_block_set+0x8e0/0x2cc4 fs/ext4/xattr.c:2043
 ext4_xattr_set_handle+0xb2c/0x12d8 fs/ext4/xattr.c:2458
 ext4_xattr_set+0x1e0/0x354 fs/ext4/xattr.c:2560
 ext4_xattr_trusted_set+0x4c/0x64 fs/ext4/xattr_trusted.c:38
 __vfs_setxattr+0x3d8/0x400 fs/xattr.c:203
 __vfs_setxattr_noperm+0x110/0x528 fs/xattr.c:237
 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:298
 vfs_setxattr+0x1a8/0x344 fs/xattr.c:324
 do_setxattr fs/xattr.c:609 [inline]
 setxattr+0x208/0x29c fs/xattr.c:632
 path_setxattr+0x17c/0x258 fs/xattr.c:651
 __do_sys_setxattr fs/xattr.c:667 [inline]
 __se_sys_setxattr fs/xattr.c:663 [inline]
 __arm64_sys_setxattr+0xbc/0xd8 fs/xattr.c:663
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x4c/0x15c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/05/06 21:55 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 14f8db1c0f9a 90c93c40 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 WARNING: locking bug in ext4_xattr_inode_update_ref
2023/01/08 00:32 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci ae87308093bc 1dac8c7a .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-gce-arm64 WARNING: locking bug in ext4_xattr_inode_update_ref
2023/05/18 17:57 linux-next 715abedee4cd 3bb7af1d .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root WARNING: locking bug in ext4_xattr_inode_update_ref
2023/05/07 13:23 linux-next 83e5775d7afd 90c93c40 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root WARNING: locking bug in ext4_xattr_inode_update_ref
* Struck through repros no longer work on HEAD.