Messages in this thread | | | Date | Tue, 5 Jul 2022 23:35:47 +0900 | Subject | Re: [PATCH] char: misc: make misc_open() and misc_register() killable | From | Tetsuo Handa <> |
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On 2022/07/05 23:16, Greg KH wrote: >> Apart from whether we should fuzz snapshot code or not, >> there seems to be a bug that causes wait_for_device_probe() to hung. > > What else is going on in the system at this point in time? Are devices > still being added as part of boot init sequences? Or has boot finished > properly and these are devices being removed?
Whatever is going on. syzkaller starts after boot has finished properly.
syzkaller is opening /dev/snapshot as one of testcases among with connecting to usb devices using /dev/raw-gadget .
An example C reproducer is https://syzkaller.appspot.com/text?tag=ReproC&x=13ef54d2b00000 .
Console output is https://syzkaller.appspot.com/x/log.txt?x=11589950080000 .
> > Some device is being probed at the moment, maybe we have a deadlock > somewhere here...
Lockdep says __device_attach() from hub_event() was in progress.
---------------------------------------- [ 237.376478][ T28] 5 locks held by kworker/1:1/26: [ 237.381526][ T28] #0: ffff888016b92538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x87a/0x1610 [ 237.392798][ T28] #1: ffffc90000c2fda8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 [ 237.406354][ T28] #2: ffff88801f7ee220 (&dev->mutex){....}-{3:3}, at: hub_event+0x1c1/0x4680 [ 237.415920][ T28] #3: ffff88801b6c6220 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7a/0x4a0 [ 237.426682][ T28] #4: ffff8880216bc1a8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x7a/0x4a0 ----------------------------------------
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