syzbot


INFO: task hung in ppp_ioctl

Status: upstream: reported on 2024/04/01 10:43
Reported-by: syzbot+1c713c558d16fa8a9dba@syzkaller.appspotmail.com
First crash: 75d, last: 75d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in ppp_ioctl ppp 1 970d 970d 0/27 auto-closed as invalid on 2022/01/17 01:14
linux-5.15 INFO: task hung in ppp_ioctl 1 3d22h 3d22h 0/3 upstream: reported on 2024/06/11 19:53

Sample crash report:
INFO: task syz-executor.3:6101 blocked for more than 143 seconds.
      Not tainted 6.1.83-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.3  state:D stack:26912 pid:6101  ppid:3565   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6693
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
 ppp_ioctl+0x10e/0x1c90 drivers/net/ppp/ppp_generic.c:712
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f343d47dda9
RSP: 002b:00007f343bffe0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f343d5ac050 RCX: 00007f343d47dda9
RDX: 0000000020000000 RSI: 0000000040047435 RDI: 0000000000000003
RBP: 00007f343d4ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f343d5ac050 R15: 00007ffd3b44e548
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d12ab10 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d12b310 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
 #0: ffffffff8d12a940 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d12a940 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d12a940 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6494
2 locks held by getty/3308:
 #0: ffff88814b5ff098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc900031262f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2188
2 locks held by syz-executor.3/6096:
1 lock held by syz-executor.3/6101:
 #0: ffffffff8db59708 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x10e/0x1c90 drivers/net/ppp/ppp_generic.c:712
1 lock held by syz-executor.4/9036:
 #0: ffffffff8db59708 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x10e/0x1c90 drivers/net/ppp/ppp_generic.c:712
1 lock held by syz-executor.4/9037:
 #0: ffffffff8db59708 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x10e/0x1c90 drivers/net/ppp/ppp_generic.c:712

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.83-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1b0/0x3f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:307
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6096 Comm: syz-executor.3 Not tainted 6.1.83-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:zone_watermark_fast+0x0/0x240 mm/page_alloc.c:4038
Code: 24 70 80 e1 07 80 c1 03 38 c1 7c 87 48 8b 7c 24 70 e8 f4 02 0c 00 e9 78 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <55> 41 57 41 56 41 55 41 54 53 48 83 ec 20 44 89 4c 24 0c 45 89 c7
RSP: 0018:ffffc9000b9e7178 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000901 RCX: 0000000000000002
RDX: 0000000000000005 RSI: 0000000000000000 RDI: ffff88813fffae00
RBP: ffffc9000b9e73f0 R08: 0000000000000901 R09: 0000000000152c40
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff9200173ce8f
R13: 0000000000000000 R14: 1ffff9200173ce8a R15: 0000000000000005
FS:  00007f343e10a6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055942ff61030 CR3: 0000000057de1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 get_page_from_freelist+0x4dc/0x3320 mm/page_alloc.c:4233
 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5545
 folio_alloc+0x1a/0x50 mm/mempolicy.c:2292
 filemap_alloc_folio+0xda/0x4f0 mm/filemap.c:971
 page_cache_ra_unbounded+0x1ee/0x7b0 mm/readahead.c:248
 do_sync_mmap_readahead+0x7ae/0x980 mm/filemap.c:3107
 filemap_fault+0x813/0x17e0 mm/filemap.c:3199
 __do_fault+0x136/0x4f0 mm/memory.c:4261
 do_read_fault mm/memory.c:4612 [inline]
 do_fault mm/memory.c:4741 [inline]
 handle_pte_fault mm/memory.c:5013 [inline]
 __handle_mm_fault mm/memory.c:5155 [inline]
 handle_mm_fault+0x3412/0x5340 mm/memory.c:5276
 do_user_addr_fault arch/x86/mm/fault.c:1371 [inline]
 handle_page_fault arch/x86/mm/fault.c:1462 [inline]
 exc_page_fault+0x26f/0x660 arch/x86/mm/fault.c:1518
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:__get_user_4+0x1c/0x30 arch/x86/lib/getuser.S:85
Code: 01 ca c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 ba fd ef ff ff ff 7f 00 00 48 39 d0 0f 83 90 00 00 00 48 19 d2 48 21 d0 0f 01 cb <8b> 10 31 c0 0f 01 ca c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 ba
RSP: 0018:ffffc9000b9e7d98 EFLAGS: 00050206
RAX: 00000000200001c0 RBX: ffff8880127f1640 RCX: ffffc9000b9e7c03
RDX: ffffffffffffffff RSI: ffffffff8aebffc0 RDI: ffffffff8b3d2b40
RBP: ffffc9000b9e7ee8 R08: dffffc0000000000 R09: fffffbfff1ce6c9e
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc9000b9e7e20
R13: 1ffff9200173cfcc R14: 00000000c004743e R15: ffff88807b169c40
 ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1041 [inline]
 ppp_ioctl+0x3a7/0x1c90 drivers/net/ppp/ppp_generic.c:716
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f343d47dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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:00007f343e10a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f343d5abf80 RCX: 00007f343d47dda9
RDX: 00000000200001c0 RSI: 00000000c004743e RDI: 0000000000000003
RBP: 00007f343d4ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f343d5abf80 R15: 00007ffd3b44e548
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/01 10:42 linux-6.1.y e5cd595e23c1 6baf5069 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in ppp_ioctl
* Struck through repros no longer work on HEAD.