[syzbot] [fat?] INFO: task hung in exfat_sync_fs

[syzbot] [fat?] INFO: task hung in exfat_sync_fs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    57012c57536f Merge tag 'net-6.5-rc4' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1675faf9a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5d10d93e1ae1f229
dashboard link: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7336195c1d93/disk-57012c57.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e7a6562e4033/vmlinux-57012c57.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7d66531ff83b/bzImage-57012c57.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com

INFO: task syz-executor.0:13703 blocked for more than 143 seconds.
      Not tainted 6.5.0-rc3-syzkaller-00123-g57012c57536f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:24584 pid:13703 ppid:20024  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1873/0x48f0 kernel/sched/core.c:6710
 schedule+0xc3/0x180 kernel/sched/core.c:6786
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6845
 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
 exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
 iterate_supers+0x12b/0x1e0 fs/super.c:744
 ksys_sync+0xdb/0x1c0 fs/sync.c:104
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0e7e87cb29
RSP: 002b:00007f0e7f52c0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f0e7e99bf80 RCX: 00007f0e7e87cb29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0e7e8c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0e7e99bf80 R15: 00007ffc7df7aba8
 </TASK>
INFO: task syz-executor.0:13704 blocked for more than 143 seconds.
      Not tainted 6.5.0-rc3-syzkaller-00123-g57012c57536f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:26152 pid:13704 ppid:20024  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1873/0x48f0 kernel/sched/core.c:6710
 schedule+0xc3/0x180 kernel/sched/core.c:6786
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6845
 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
 exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
 iterate_supers+0x12b/0x1e0 fs/super.c:744
 ksys_sync+0xdb/0x1c0 fs/sync.c:104
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0e7e87cb29
RSP: 002b:00007f0e7f50b0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f0e7e99c050 RCX: 00007f0e7e87cb29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0e7e8c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f0e7e99c050 R15: 00007ffc7df7aba8
 </TASK>
INFO: task syz-executor.0:13705 blocked for more than 144 seconds.
      Not tainted 6.5.0-rc3-syzkaller-00123-g57012c57536f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:27336 pid:13705 ppid:20024  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1873/0x48f0 kernel/sched/core.c:6710
 schedule+0xc3/0x180 kernel/sched/core.c:6786
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6845
 __mutex_lock_common+0xe33/0x2530 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
 exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
 iterate_supers+0x12b/0x1e0 fs/super.c:744
 ksys_sync+0xdb/0x1c0 fs/sync.c:104
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0e7e87cb29
RSP: 002b:00007f0e750060c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f0e7e99c120 RCX: 00007f0e7e87cb29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0e7e8c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f0e7e99c120 R15: 00007ffc7df7aba8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/13:
 #0: ffffffff8d328db0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:522
1 lock held by rcu_tasks_trace/14:
 #0: ffffffff8d329170 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:522
1 lock held by khungtaskd/27:
 #0: ffffffff8d328be0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/4768:
 #0: ffff88802cdfa098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900015a02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b1/0x1dc0 drivers/tty/n_tty.c:2187
5 locks held by kworker/u4:8/6147:
 #0: ffff8880b993bf98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
 #1: ffff8880b99287c8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x441/0x770 kernel/sched/psi.c:999
 #2: ffff8880b99295d8 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x692/0xf40 kernel/time/timer.c:1112
 #3: ffffffff922b52c0 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x163/0x530 lib/debugobjects.c:717
 #4: ffffffff8d1da0a8 (text_mutex){+.+.}-{3:3}, at: arch_jump_label_transform_apply+0x12/0x30 arch/x86/kernel/jump_label.c:145
3 locks held by syz-executor.4/5979:
2 locks held by syz-executor.0/13703:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/13704:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/13705:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/13946:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/14038:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/14039:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by syz-executor.0/14040:
 #0: ffff8880797680e0 (&type->s_umount_key#49){++++}-{3:3}, at: iterate_supers+0xb0/0x1e0 fs/super.c:742
 #1: ffff88807976a0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_sync_fs+0x6b/0x100 fs/exfat/super.c:65
2 locks held by dhcpcd/14047:
 #0: ffff88803d73e130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1708 [inline]
 #0: ffff88803d73e130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xc10 net/packet/af_packet.c:3202
 #1: ffffffff8d32e278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:293 [inline]
 #1: ffffffff8d32e278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a3/0x890 kernel/rcu/tree_exp.h:992

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.5.0-rc3-syzkaller-00123-g57012c57536f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x498/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x187/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xec2/0xf00 kernel/hung_task.c:379
 kthread+0x2b8/0x350 kernel/kthread.c:389
 ret_from_fork+0x2e/0x60 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:296
RIP: 0000:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:0000000000000000 EFLAGS: 00000000 ORIG_RAX: 0000000000000000
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4453 Comm: syslogd Not tainted 6.5.0-rc3-syzkaller-00123-g57012c57536f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
RIP: 0010:memset_orig+0x33/0xac arch/x86/lib/memset_64.S:67
Code: b6 ce 48 b8 01 01 01 01 01 01 01 01 48 0f af c1 41 89 f9 41 83 e1 07 75 6c 48 89 d1 48 c1 e9 06 74 35 0f 1f 44 00 00 48 ff c9 <48> 89 07 48 89 47 08 48 89 47 10 48 89 47 18 48 89 47 20 48 89 47
RSP: 0018:ffffc90005697418 EFLAGS: 00000247
RAX: 0000000000000000 RBX: ffff88807e278000 RCX: 0000000000000000
RDX: 0000000000000060 RSI: 0000000000000000 RDI: ffffc90005697480
RBP: dffffc0000000000 R08: ffffc900056974df R09: 0000000000000000
R10: ffffc90005697480 R11: fffff52000ad2e9c R12: 0000000000000000
R13: ffffffff817a0b80 R14: ffffc90005697480 R15: 0000000000000000
FS:  00007f0dc2ea9380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005611df817600 CR3: 0000000028c84000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __unwind_start+0x36/0x720 arch/x86/kernel/unwind_orc.c:688
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0xdf/0x140 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x117/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1792 [inline]
 slab_free_freelist_hook mm/slub.c:1818 [inline]
 slab_free mm/slub.c:3801 [inline]
 __kmem_cache_free+0x25f/0x3b0 mm/slub.c:3814
 skb_kfree_head net/core/skbuff.c:894 [inline]
 skb_free_head net/core/skbuff.c:906 [inline]
 skb_release_data+0x660/0x850 net/core/skbuff.c:936
 skb_release_all net/core/skbuff.c:1002 [inline]
 __kfree_skb net/core/skbuff.c:1016 [inline]
 consume_skb+0xb3/0x150 net/core/skbuff.c:1232
 __unix_dgram_recvmsg+0xcb7/0x1260 net/unix/af_unix.c:2442
 sock_recvmsg_nosec net/socket.c:1020 [inline]
 sock_recvmsg net/socket.c:1041 [inline]
 sock_read_iter+0x3ab/0x500 net/socket.c:1107
 call_read_iter include/linux/fs.h:1865 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x795/0xb00 fs/read_write.c:470
 ksys_read+0x1a0/0x2c0 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0dc2ffdb6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc321f7068 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f0dc2ffdb6a
RDX: 00000000000000ff RSI: 0000558a4fb90950 RDI: 0000000000000000
RBP: 0000558a4fb90910 R08: 0000000000000001 R09: 0000000000000000
R10: 00007f0dc319c3a3 R11: 0000000000000246 R12: 0000558a4fb9099d
R13: 0000558a4fb90950 R14: 0000000000000000 R15: 00007f0dc31daa80
 </TASK>


---
This report is generated by a bot. It may contain errors.
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syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [exfat?] INFO: task hung in exfat_sync_fs

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    f92f4749861b Merge tag 'clk-fixes-for-linus' of git://git...
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=165e73e8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c7c9f223bfe8924e
dashboard link: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1619bb30580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=115e73e8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5b8875fea73b/disk-f92f4749.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bf1ea2d28b68/vmlinux-f92f4749.xz
kernel image: https://storage.googleapis.com/syzbot-assets/21f786c9f90d/bzImage-f92f4749.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d6e372cd93dd/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com

INFO: task syz-executor405:5841 blocked for more than 143 seconds.
      Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor405 state:D stack:27504 pid:5841  tgid:5838  ppid:5837   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x17fb/0x4be0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6905
 __mutex_lock_common kernel/locking/mutex.c:665 [inline]
 __mutex_lock+0x7e7/0xee0 kernel/locking/mutex.c:735
 exfat_sync_fs+0xb0/0x160 fs/exfat/super.c:56
 iterate_supers+0xc6/0x190 fs/super.c:934
 ksys_sync+0xdb/0x1c0 fs/sync.c:104
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff13f9f4849
RSP: 002b:00007ff13f98a218 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007ff13fa7c6d8 RCX: 00007ff13f9f4849
RDX: 00007ff13f9cdfb6 RSI: 0000000000000000 RDI: 00007ff13f98afb0
RBP: 00007ff13fa7c6d0 R08: 00007ffce2fc7077 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff13fa48086
R13: 00007ff13fa4807e R14: 633d73726f727265 R15: 0030656c69662f2e
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937ae0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
2 locks held by getty/5572:
 #0: ffff88814d4a10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032fb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
3 locks held by syz-executor405/5840:
2 locks held by syz-executor405/5841:
 #0: ffff88807d95a0e0 (&type->s_umount_key#64){.+.+}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88807d95a0e0 (&type->s_umount_key#64){.+.+}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
 #1: ffff88807d9580e8 (&sbi->s_lock){+.+.}-{4:4}, at: exfat_sync_fs+0xb0/0x160 fs/exfat/super.c:56

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xff6/0x1040 kernel/hung_task.c:397
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5840 Comm: syz-executor405 Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0x10/0xb0 kernel/rcu/tree.c:737
Code: 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 65 ff 05 48 db 7e 7e <e8> db 5d 3b 0a 89 c3 83 f8 08 73 7a 49 bf 00 00 00 00 00 fc ff df
RSP: 0018:ffffc9000401f488 EFLAGS: 00000083
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff81a7289c
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90183af0
RBP: ffffc9000401f5f8 R08: ffffffff90183af7 R09: 1ffffffff203075e
R10: dffffc0000000000 R11: fffffbfff203075f R12: 0000000000000246
R13: dffffc0000000000 R14: 0000000000000200 R15: 00000000000000a0
FS:  00007ff13f9ab6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555571eef738 CR3: 0000000073fd8000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 trace_irq_disable+0x3b/0x120 include/trace/events/preemptirq.h:36
 lookup_bh_lru fs/buffer.c:1359 [inline]
 __find_get_block+0x190/0x1150 fs/buffer.c:1394
 bdev_getblk+0x33/0x670 fs/buffer.c:1425
 __bread_gfp+0x86/0x400 fs/buffer.c:1485
 sb_bread include/linux/buffer_head.h:346 [inline]
 exfat_get_dentry+0x53b/0x730 fs/exfat/dir.c:672
 exfat_readdir fs/exfat/dir.c:118 [inline]
 exfat_iterate+0x9f9/0x2ce0 fs/exfat/dir.c:242
 wrap_directory_iterator+0x91/0xd0 fs/readdir.c:65
 iterate_dir+0x571/0x800 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:403 [inline]
 __se_sys_getdents64+0x1e2/0x4b0 fs/readdir.c:389
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff13f9f4849
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 18 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff13f9ab218 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007ff13fa7c6c8 RCX: 00007ff13f9f4849
RDX: 0000000000001000 RSI: 0000000020000f80 RDI: 0000000000000004
RBP: 00007ff13fa7c6c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff13fa48086
R13: 00007ff13fa4807e R14: 633d73726f727265 R15: 0030656c69662f2e
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.207 msecs


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

Re: [syzbot] [exfat?] INFO: task hung in exfat_sync_fs

[Yuezhang.Mo]

[-- Attachment #1: Type: text/plain, Size: 9 bytes --]

#syz test

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: v1-0001-exfat-add-loop-chek-for-the-cluster-chain-of-root.patch --]
[-- Type: text/x-patch; name="v1-0001-exfat-add-loop-chek-for-the-cluster-chain-of-root.patch", Size: 613 bytes --]

From e89c336b835e5b9170b518cf5eea98ea53f49f4b Mon Sep 17 00:00:00 2001
From: Yuezhang Mo <Yuezhang.Mo@sony.com>
Date: Thu, 12 Dec 2024 11:15:37 +0800
Subject: [PATCH v1] exfat: add loop chek for the cluster chain of root

---
 fs/exfat/fatent.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
index 5d8b7413d80d..0b49e6878222 100644
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -455,6 +455,9 @@ int exfat_count_num_clusters(struct super_block *sb,
 			break;
 	}
 
+	if (i == sbi->num_clusters)
+		return -EIO;
+
 	*ret_count = count;
 	return 0;
 }
-- 
2.43.0

Re: [syzbot] [exfat?] INFO: task hung in exfat_sync_fs

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com
Tested-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com

Tested on:

commit:         231825b2 Revert "unicode: Don't special case ignorable..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f97b30580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c7c9f223bfe8924e
dashboard link: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16e77544580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [exfat?] INFO: task hung in exfat_sync_fs

[Yuezhang.Mo]

[-- Attachment #1: Type: text/plain, Size: 13 bytes --]

#syz test


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: v1-0001-exfat-fix-the-infinite-loop-in-exfat_readdir.patch --]
[-- Type: text/x-patch; name="v1-0001-exfat-fix-the-infinite-loop-in-exfat_readdir.patch", Size: 1355 bytes --]

From 2ba96e6e4923f0ad0d1bbcc077e887d5d7031bc0 Mon Sep 17 00:00:00 2001
From: Yuezhang Mo <Yuezhang.Mo@sony.com>
Date: Fri, 13 Dec 2024 13:08:37 +0800
Subject: [PATCH v1] exfat: fix the infinite loop in exfat_readdir()

If a cluster is linked to itself in the cluster chain, and there
is an unused directory entry in the cluster, 'dentry' will not be
incremented, causing condition 'dentry < max_dentries' unable to
prevent an infinite loop.

The infinite loop in exfat_readdir() causes s_lock not to be released,
This infinite loop causes s_lock not to be released, and other tasks
will hang, such as exfat_sync_fs().

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
---
 fs/exfat/dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index fe0a9b8a0cd0..3103b932b674 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -122,7 +122,7 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent
 			type = exfat_get_entry_type(ep);
 			if (type == TYPE_UNUSED) {
 				brelse(bh);
-				break;
+				goto out;
 			}
 
 			if (type != TYPE_FILE && type != TYPE_DIR) {
@@ -170,6 +170,7 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent
 		}
 	}
 
+out:
 	dir_entry->namebuf.lfn[0] = '\0';
 	*cpos = EXFAT_DEN_TO_B(dentry);
 	return 0;
-- 
2.43.0

Re: [syzbot] [exfat?] INFO: task hung in exfat_sync_fs

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com
Tested-by: syzbot+205c2644abdff9d3f9fc@syzkaller.appspotmail.com

Tested on:

commit:         f932fb9b Merge tag 'v6.13-rc2-ksmbd-server-fixes' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13af6a0f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c7c9f223bfe8924e
dashboard link: https://syzkaller.appspot.com/bug?extid=205c2644abdff9d3f9fc
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16738730580000

Note: testing is done by a robot and is best-effort only.