Re: [syzbot] [input?] possible deadlock in input_ff_flush

Hillf Danton
2025-01-06T11:08:44Z

On Sun, 05 Jan 2025 04:40:19 -0800
> syzbot found the following issue on:
>
> HEAD commit: ccb98ccef0e5 Merge tag 'platform-drivers-x86-v6.13-4' of g..
> git tree: upstream
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17bd56df980000

#syz test

--- x/drivers/input/input.c
+++ y/drivers/input/input.c
@@ -642,17 +642,11 @@ EXPORT_SYMBOL(input_open_device);
int input_flush_device(struct input_handle *handle, struct file *file)
{
struct input_dev *dev = handle->dev;
- int retval;
-
- retval = mutex_lock_interruptible(&dev->mutex);
- if (retval)
- return retval;

if (dev->flush)
- retval = dev->flush(dev, file);
+ return dev->flush(dev, file);

- mutex_unlock(&dev->mutex);
- return retval;
+ return 0;
}
EXPORT_SYMBOL(input_flush_device);

--- x/mm/vmstat.c
+++ y/mm/vmstat.c
@@ -2122,9 +2122,11 @@ static void __init start_shepherd_timer(
{
int cpu;

- for_each_possible_cpu(cpu)
+ for_each_possible_cpu(cpu) {
INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
vmstat_update);
+ disable_delayed_work(per_cpu_ptr(&vmstat_work, cpu));
+ }

schedule_delayed_work(&shepherd,
round_jiffies_relative(sysctl_stat_interval));
--