Hello,
syzbot has tested the proposed patch but the reproducer still triggered
crash:
INFO: rcu detected stall in dummy_timer
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 3-1:0.0: non-zero urb status (-71)
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 1-...!: (8177 ticks this GP) idle=78e/1/0x4000000000000004
softirq=3439/3439 fqs=0
(t=10502 jiffies g=2653 q=23)
rcu: rcu_sched kthread starved for 10504 jiffies! g2653 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_sched R running task 29744 10 2 0x80004000
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x440/0xb20 kernel/time/timer.c:1895
rcu_gp_fqs_loop kernel/rcu/tree.c:1639 [inline]
rcu_gp_kthread+0xaff/0x29e0 kernel/rcu/tree.c:1799
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 1
CPU: 1 PID: 1737 Comm: kworker/1:3 Not tainted 5.4.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x55/0x96 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b0/0x1c7 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x169/0x1b3 kernel/rcu/tree_stall.h:254
print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
rcu_pending kernel/rcu/tree.c:2795 [inline]
rcu_sched_clock_irq.cold+0x4da/0x936 kernel/rcu/tree.c:2244
update_process_times+0x25/0x60 kernel/time/timer.c:1726
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:167
tick_sched_timer+0x42/0x130 kernel/time/tick-sched.c:1299
__run_hrtimer kernel/time/hrtimer.c:1514 [inline]
__hrtimer_run_queues+0x303/0xc60 kernel/time/hrtimer.c:1576
hrtimer_interrupt+0x2e8/0x730 kernel/time/hrtimer.c:1638
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
smp_apic_timer_interrupt+0xf5/0x500 arch/x86/kernel/apic/apic.c:1135
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:85 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160
[inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x40/0x50
kernel/locking/spinlock.c:191
Code: e8 95 14 b3 fb 48 89 ef e8 6d f3 b3 fb f6 c7 02 75 11 53 9d e8 61 ba
d0 fb 65 ff 0d a2 67 8f 7a 5b 5d c3 e8 02 be d0 fb 53 9d <eb> ed 0f 1f 40
00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 fd 65 ff
RSP: 0018:ffff8881db309b08 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: 0000000000000206 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8881d065084c
RBP: ffff8881d50f4000 R08: ffff8881d0650000 R09: fffffbfff11b23b8
R10: fffffbfff11b23b7 R11: ffffffff88d91dbf R12: 0000000000000080
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8881d46bcd00
spin_unlock_irqrestore include/linux/spinlock.h:393 [inline]
dummy_timer+0x131b/0x2fa2 drivers/usb/gadget/udc/dummy_hcd.c:1980
call_timer_fn+0x179/0x650 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0x5e3/0x1490 kernel/time/timer.c:1786
__do_softirq+0x221/0x912 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x178/0x1a0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x12f/0x500 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:85 [inline]
RIP: 0010:console_unlock+0xb4f/0xc40 kernel/printk/printk.c:2477
Code: 32 fe ff ff e8 a2 ae 15 00 48 8b bc 24 80 00 00 00 e8 b5 dd ff ff e9
29 fb ff ff e8 8b ae 15 00 e8 06 db 1a 00 ff 74 24 30 9d <e9> 15 fb ff ff
e8 67 f0 3c 00 e9 de f6 ff ff e8 6d f0 3c 00 e9 98
RSP: 0018:ffff8881c06beda0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: 0000000000000200 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffff8881d06508f0 RDI: ffff8881d065084c
RBP: 0000000000000001 R08: ffff8881d0650000 R09: fffffbfff11b23ae
R10: fffffbfff11b23ad R11: ffffffff88d91d6f R12: 0000000000000047
R13: dffffc0000000000 R14: ffffffff8293f390 R15: ffffffff87077070
vprintk_emit+0x171/0x3e0 kernel/printk/printk.c:1996
dev_vprintk_emit+0x4fc/0x541 drivers/base/core.c:3312
dev_printk_emit+0xba/0xf1 drivers/base/core.c:3323
__dev_printk+0x1db/0x203 drivers/base/core.c:3335
_dev_warn+0xd7/0x109 drivers/base/core.c:3379
si470x_set_report.isra.0.constprop.0.cold+0x32/0x41
drivers/media/radio/si470x/radio-si470x-usb.c:234
si470x_set_register+0x11c/0x180
drivers/media/radio/si470x/radio-si470x-usb.c:269
si470x_start+0x72/0x2bf
drivers/media/radio/si470x/radio-si470x-common.c:374
si470x_start_usb+0x507/0x53d
drivers/media/radio/si470x/radio-si470x-usb.c:549
si470x_usb_driver_probe.cold+0x6e5/0x8b2
drivers/media/radio/si470x/radio-si470x-usb.c:737
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x104/0x210 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0xae6/0x16f0 drivers/base/core.c:2201
usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x6d0 drivers/base/dd.c:548
driver_probe_device+0x104/0x210 drivers/base/dd.c:721
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x360 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0xae6/0x16f0 drivers/base/core.c:2201
usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5183 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5323 [inline]
port_event drivers/usb/core/hub.c:5469 [inline]
hub_event+0x1dd0/0x37e0 drivers/usb/core/hub.c:5551
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 3-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 3-1:0.0: non-zero urb status (-71)
radio-si470x 3-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 3-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 6-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 6-1:0.0: non-zero urb status (-71)
radio-si470x 1-1:0.0: non-zero urb status (-71)
radio-si470x 6-1:0.0: non-zero urb status (-71)
radio-si470x 2-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 2-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 2-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 2-1:0.0: non-zero urb status (-71)
radio-si470x 5-1:0.0: non-zero urb status (-71)
radio-si470x 2-1:0.0: non-zero urb status (-71)
radio-si470x 4-1:0.0: non-zero urb status (-71)
radio-si470x 6-1:0.0: non-zero urb status (-71)
radio-si470x 6-1:0.0: non-zero urb status (-71)
Tested on:
commit: 22be26f7 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11821c22e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=387eccb7ac68ec5
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca7a12fd736d93e0232
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=12ae33ace00000
