[syzbot] possible deadlock in ___bpf_prog_run

syzbot
2022-04-29T22:39:28Z

Hello,

syzbot found the following issue on:

HEAD commit: af2d861d4cd2 Linux 5.18-rc4
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1180aa00f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4071c85377b36266
dashboard link: https://syzkaller.appspot.com/bug?extid=e8a9ac8d099f6b5efa84
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e8a9ac8d099f6b5efa84@syzkaller.appspotmail.com

------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
5.18.0-rc4-syzkaller #0 Tainted: G S
------------------------------------------------------
rcu_preempt/18 is trying to acquire lock:
ffffffff8bd6e0b8 ((console_sem).lock){-.-.}-{2:2}, at: down_trylock+0xe/0x60 kernel/locking/semaphore.c:138

but task is already holding lock:
ffffffff8be04df8 (trace_printk_lock){....}-{2:2}, at: ____bpf_trace_printk kernel/trace/bpf_trace.c:385 [inline]
ffffffff8be04df8 (trace_printk_lock){....}-{2:2}, at: bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:371

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (trace_printk_lock){....}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
____bpf_trace_printk kernel/trace/bpf_trace.c:385 [inline]
bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:371
___bpf_prog_run+0x3592/0x77d0 kernel/bpf/core.c:1835
__bpf_prog_run32+0x8a/0xd0 kernel/bpf/core.c:2062
bpf_dispatcher_nop_func include/linux/bpf.h:804 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2022 [inline]
bpf_trace_run4+0x124/0x360 kernel/trace/bpf_trace.c:2061
__bpf_trace_sched_switch+0x115/0x160 include/trace/events/sched.h:222
__traceiter_sched_switch+0x68/0xb0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x1543/0x4cc0 kernel/sched/core.c:6385
preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6553
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
try_to_wake_up+0xa04/0x1800 kernel/sched/core.c:4204
wake_up_process kernel/sched/core.c:4282 [inline]
wake_up_q+0x7e/0xf0 kernel/sched/core.c:1029
futex_wake+0x3e9/0x490 kernel/futex/waitwake.c:184
do_futex+0x266/0x300 kernel/futex/syscalls.c:111
__do_sys_futex kernel/futex/syscalls.c:183 [inline]
__se_sys_futex kernel/futex/syscalls.c:164 [inline]
__x64_sys_futex+0x1b0/0x4a0 kernel/futex/syscalls.c:164
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (&rq->__lock){-.-.}-{2:2}:
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:378
raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:554
raw_spin_rq_lock kernel/sched/sched.h:1297 [inline]
rq_lock kernel/sched/sched.h:1595 [inline]
task_fork_fair+0x68/0x520 kernel/sched/fair.c:11236
sched_cgroup_fork+0x340/0x480 kernel/sched/core.c:4546
copy_process+0x42f0/0x6fe0 kernel/fork.c:2351
kernel_clone+0xe7/0xab0 kernel/fork.c:2639
kernel_thread+0xb5/0xf0 kernel/fork.c:2691
rest_init+0x23/0x3e0 init/main.c:691
start_kernel+0x47f/0x4a0 init/main.c:1140
secondary_startup_64_no_verify+0xc3/0xcb

-> #1 (&p->pi_lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
try_to_wake_up+0xaa/0x1800 kernel/sched/core.c:4082
up+0x75/0xb0 kernel/locking/semaphore.c:190
__up_console_sem+0xa4/0xc0 kernel/printk/printk.c:263
console_unlock+0x62c/0xdd0 kernel/printk/printk.c:2794
vga_remove_vgacon drivers/pci/vgaarb.c:189 [inline]
vga_remove_vgacon.cold+0x99/0x9e drivers/pci/vgaarb.c:170
drm_aperture_remove_conflicting_pci_framebuffers+0x188/0x230 drivers/gpu/drm/drm_aperture.c:350
virtio_gpu_pci_quirk drivers/gpu/drm/virtio/virtgpu_drv.c:61 [inline]
virtio_gpu_probe.cold+0x16a/0x189 drivers/gpu/drm/virtio/virtgpu_drv.c:118
virtio_dev_probe+0x577/0x870 drivers/virtio/virtio.c:295
call_driver_probe drivers/base/dd.c:542 [inline]
really_probe+0x23e/0xb20 drivers/base/dd.c:621
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:752
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:782
__driver_attach+0x22d/0x4e0 drivers/base/dd.c:1141
bus_for_each_dev+0x147/0x1d0 drivers/base/bus.c:301
bus_add_driver+0x41d/0x630 drivers/base/bus.c:618
driver_register+0x220/0x3a0 drivers/base/driver.c:171
do_one_initcall+0x103/0x650 init/main.c:1298
do_initcall_level init/main.c:1371 [inline]
do_initcalls init/main.c:1387 [inline]
do_basic_setup init/main.c:1406 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1613
kernel_init+0x1a/0x1d0 init/main.c:1502
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

-> #0 ((console_sem).lock){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3065 [inline]
check_prevs_add kernel/locking/lockdep.c:3188 [inline]
validate_chain kernel/locking/lockdep.c:3803 [inline]
__lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029
lock_acquire kernel/locking/lockdep.c:5641 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
down_trylock+0xe/0x60 kernel/locking/semaphore.c:138
__down_trylock_console_sem+0x40/0x120 kernel/printk/printk.c:246
console_trylock kernel/printk/printk.c:2581 [inline]
console_trylock_spinning kernel/printk/printk.c:1856 [inline]
vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2271
vprintk+0x80/0x90 kernel/printk/printk_safe.c:50
_printk+0xba/0xed kernel/printk/printk.c:2293
__warn_printk+0x9b/0xf3 kernel/panic.c:638
rb_check_timestamp kernel/trace/ring_buffer.c:2734 [inline]
rb_add_timestamp kernel/trace/ring_buffer.c:2772 [inline]
rb_update_event kernel/trace/ring_buffer.c:2809 [inline]
__rb_reserve_next+0x121a/0x1630 kernel/trace/ring_buffer.c:3565
rb_reserve_next_event kernel/trace/ring_buffer.c:3635 [inline]
ring_buffer_lock_reserve+0x44f/0xfa0 kernel/trace/ring_buffer.c:3694
__trace_buffer_lock_reserve kernel/trace/trace.c:949 [inline]
trace_event_buffer_lock_reserve+0x11e/0x730 kernel/trace/trace.c:2821
trace_event_buffer_reserve+0x248/0x3c0 kernel/trace/trace_events.c:496
trace_event_raw_event_bpf_trace_printk+0xe9/0x1f0 kernel/trace/./bpf_trace.h:11
trace_bpf_trace_printk+0x116/0x220 kernel/trace/bpf_trace.h:11
____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline]
bpf_trace_printk+0xfa/0x170 kernel/trace/bpf_trace.c:371
___bpf_prog_run+0x3592/0x77d0 kernel/bpf/core.c:1835
__bpf_prog_run32+0x8a/0xd0 kernel/bpf/core.c:2062
bpf_dispatcher_nop_func include/linux/bpf.h:804 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2022 [inline]
bpf_trace_run4+0x124/0x360 kernel/trace/bpf_trace.c:2061
__bpf_trace_sched_switch+0x115/0x160 include/trace/events/sched.h:222
__traceiter_sched_switch+0x68/0xb0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x1543/0x4cc0 kernel/sched/core.c:6385
schedule+0xd2/0x1f0 kernel/sched/core.c:6460
schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1884
rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1971
rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2144
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

other info that might help us debug this:

Chain exists of:
(console_sem).lock --> &rq->__lock --> trace_printk_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(trace_printk_lock);
lock(&rq->__lock);
lock(trace_printk_lock);
lock((console_sem).lock);

*** DEADLOCK ***

3 locks held by rcu_preempt/18:
#0: ffff88802cc3a098 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:554
#1: ffffffff8bd7f5e0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0x0/0x360 include/linux/filter.h:628
#2: ffffffff8be04df8 (trace_printk_lock){....}-{2:2}, at: ____bpf_trace_printk kernel/trace/bpf_trace.c:385 [inline]
#2: ffffffff8be04df8 (trace_printk_lock){....}-{2:2}, at: bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:371

stack backtrace:
CPU: 2 PID: 18 Comm: rcu_preempt Tainted: G S 5.18.0-rc4-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2145
check_prev_add kernel/locking/lockdep.c:3065 [inline]
check_prevs_add kernel/locking/lockdep.c:3188 [inline]
validate_chain kernel/locking/lockdep.c:3803 [inline]
__lock_acquire+0x2ac6/0x56c0 kernel/locking/lockdep.c:5029
lock_acquire kernel/locking/lockdep.c:5641 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5606
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
down_trylock+0xe/0x60 kernel/locking/semaphore.c:138
__down_trylock_console_sem+0x40/0x120 kernel/printk/printk.c:246
console_trylock kernel/printk/printk.c:2581 [inline]
console_trylock_spinning kernel/printk/printk.c:1856 [inline]
vprintk_emit+0x162/0x5f0 kernel/printk/printk.c:2271
vprintk+0x80/0x90 kernel/printk/printk_safe.c:50
_printk+0xba/0xed kernel/printk/printk.c:2293
__warn_printk+0x9b/0xf3 kernel/panic.c:638
rb_check_timestamp kernel/trace/ring_buffer.c:2734 [inline]
rb_add_timestamp kernel/trace/ring_buffer.c:2772 [inline]
rb_update_event kernel/trace/ring_buffer.c:2809 [inline]
__rb_reserve_next+0x121a/0x1630 kernel/trace/ring_buffer.c:3565
rb_reserve_next_event kernel/trace/ring_buffer.c:3635 [inline]
ring_buffer_lock_reserve+0x44f/0xfa0 kernel/trace/ring_buffer.c:3694
__trace_buffer_lock_reserve kernel/trace/trace.c:949 [inline]
trace_event_buffer_lock_reserve+0x11e/0x730 kernel/trace/trace.c:2821
trace_event_buffer_reserve+0x248/0x3c0 kernel/trace/trace_events.c:496
trace_event_raw_event_bpf_trace_printk+0xe9/0x1f0 kernel/trace/./bpf_trace.h:11
trace_bpf_trace_printk+0x116/0x220 kernel/trace/bpf_trace.h:11
____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline]
bpf_trace_printk+0xfa/0x170 kernel/trace/bpf_trace.c:371
___bpf_prog_run+0x3592/0x77d0 kernel/bpf/core.c:1835
__bpf_prog_run32+0x8a/0xd0 kernel/bpf/core.c:2062
bpf_dispatcher_nop_func include/linux/bpf.h:804 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2022 [inline]
bpf_trace_run4+0x124/0x360 kernel/trace/bpf_trace.c:2061
__bpf_trace_sched_switch+0x115/0x160 include/trace/events/sched.h:222
__traceiter_sched_switch+0x68/0xb0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x1543/0x4cc0 kernel/sched/core.c:6385
schedule+0xd2/0x1f0 kernel/sched/core.c:6460
schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1884
rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1971
rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2144
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
</TASK>
Delta way too big! 8020330161787334413 ts=8020330481964229010 before=320176894597 after=320176894597 write stamp=8020330481964229010
WARNING: CPU: 2 PID: 18 at kernel/trace/ring_buffer.c:2734 rb_check_timestamp kernel/trace/ring_buffer.c:2734 [inline]
WARNING: CPU: 2 PID: 18 at kernel/trace/ring_buffer.c:2734 rb_add_timestamp kernel/trace/ring_buffer.c:2772 [inline]
WARNING: CPU: 2 PID: 18 at kernel/trace/ring_buffer.c:2734 rb_update_event kernel/trace/ring_buffer.c:2809 [inline]
WARNING: CPU: 2 PID: 18 at kernel/trace/ring_buffer.c:2734 __rb_reserve_next+0x121a/0x1630 kernel/trace/ring_buffer.c:3565
Modules linked in:
CPU: 2 PID: 18 Comm: rcu_preempt Tainted: G S 5.18.0-rc4-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:rb_check_timestamp kernel/trace/ring_buffer.c:2734 [inline]
RIP: 0010:rb_add_timestamp kernel/trace/ring_buffer.c:2772 [inline]
RIP: 0010:rb_update_event kernel/trace/ring_buffer.c:2809 [inline]
RIP: 0010:__rb_reserve_next+0x121a/0x1630 kernel/trace/ring_buffer.c:3565
Code: 80 3c 01 00 0f 85 98 02 00 00 ff 74 24 40 49 89 d8 4c 89 f1 48 c7 c7 00 17 d1 89 49 8b 74 24 08 4c 8b 4c 24 20 e8 2d da a9 07 <0f> 0b 58 e9 89 fe ff ff e8 39 6c 48 00 e9 0f ee ff ff 48 89 ef e8
RSP: 0018:ffffc9000065f388 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000004a8c07b285 RCX: 0000000000000000
RDX: ffff8880118da200 RSI: ffffffff815f3b38 RDI: fffff520000cbe63
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815ee50e R11: 0000000000000000 R12: ffffc9000065f4c0
R13: ffff888011b30000 R14: 0000004a8c07b285 R15: 0000000000000b40
FS: 0000000000000000(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfc11681b8 CR3: 0000000068ca0000 CR4: 0000000000150ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rb_reserve_next_event kernel/trace/ring_buffer.c:3635 [inline]
ring_buffer_lock_reserve+0x44f/0xfa0 kernel/trace/ring_buffer.c:3694
__trace_buffer_lock_reserve kernel/trace/trace.c:949 [inline]
trace_event_buffer_lock_reserve+0x11e/0x730 kernel/trace/trace.c:2821
trace_event_buffer_reserve+0x248/0x3c0 kernel/trace/trace_events.c:496
trace_event_raw_event_bpf_trace_printk+0xe9/0x1f0 kernel/trace/./bpf_trace.h:11
trace_bpf_trace_printk+0x116/0x220 kernel/trace/bpf_trace.h:11
____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline]
bpf_trace_printk+0xfa/0x170 kernel/trace/bpf_trace.c:371
___bpf_prog_run+0x3592/0x77d0 kernel/bpf/core.c:1835
__bpf_prog_run32+0x8a/0xd0 kernel/bpf/core.c:2062
bpf_dispatcher_nop_func include/linux/bpf.h:804 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2022 [inline]
bpf_trace_run4+0x124/0x360 kernel/trace/bpf_trace.c:2061
__bpf_trace_sched_switch+0x115/0x160 include/trace/events/sched.h:222
__traceiter_sched_switch+0x68/0xb0 include/trace/events/sched.h:222
trace_sched_switch include/trace/events/sched.h:222 [inline]
__schedule+0x1543/0x4cc0 kernel/sched/core.c:6385
schedule+0xd2/0x1f0 kernel/sched/core.c:6460
schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1884
rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1971
rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2144
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
</TASK>

---
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