Am Dienstag, den 06.08.2019, 14:50 +0200 schrieb Andrey Konovalov: > On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <oneukum@xxxxxxxx> wrote: > > > > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern: > > > > > > I think this must be caused by an unbalanced refcount. That is, > > > something must drop one more reference to the device than it takes. > > > That would explain why the invalid access occurs inside a single > > > bus_remove_device() call, between the klist_del() and > > > device_release_driver(). > > > > > > The kernel log indicates that the device was probed by rndis_wlan, > > > rndis_host, and cdc_acm, all of which got errors because of the > > > device's bogus descriptors. Probably one of them is messing up the > > > refcount. > > > > Hi, > > > > you made me look at cdc-acm. I suspect > > > > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail") > > > > is buggy decrementing the refcount on the interface in destroy() > > even before the refcount is increased. > > > > Unfortunately I cannot tell from the bug report how many and which > > interfaces the emulated test device has. Hence it is unclear to me, > > when exactly probe() would fail cdc-acm. > > > > If you agree. I am attaching a putative fix. > > Let's see if it fixes the issue. > > #syz fix: https://github.com/google/kasan.git 6a3599ce Hi, did this ever produce a result? I saw none. Regards Oliver