Happy to receive your reply! I will double-check its validity. If there is still a problem, I will contact the midi development team. Best wishes! Rondreis On Wed, Sep 14, 2022 at 10:02 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, Sep 14, 2022 at 08:49:49PM +0800, Rondreis wrote: > > Hello, > > > > When fuzzing the Linux kernel driver v6.0-rc4, the following crash was > > triggered. > > > > HEAD commit: 7e18e42e4b280c85b76967a9106a13ca61c16179 > > git tree: upstream > > > > kernel config: https://pastebin.com/raw/xtrgsXP3 > > C reproducer: https://pastebin.com/raw/C1xYEf7Q > > console output: https://pastebin.com/raw/3RLhvQHE > > > > Basically, in the c reproducer, we use the gadget module to emulate > > attaching a USB device(vendor id: 0x403, product id: 0xff3d, with the > > midi function) and executing some simple sequence of system calls. > > To reproduce this crash, we utilize a third-party library to emulate > > the attaching process: https://github.com/linux-usb-gadgets/libusbgx. > > Just clone this repository, install it, and compile the c > > reproducer with ``` gcc crash.c -lusbgx -lconfig -o crash ``` will do > > the trick. > > > > I would appreciate it if you have any idea how to solve this bug. > > > > The crash report is as follows: > > > > > > ============================================ > > WARNING: possible recursive locking detected > > 6.0.0-rc4+ #20 Not tainted > > -------------------------------------------- > > kworker/0:1H/9 is trying to acquire lock: > > ffff888057ed9228 (&midi->transmit_lock){....}-{2:2}, at: > > f_midi_transmit+0x18c/0x1460 drivers/usb/gadget/function/f_midi.c:683 > > > > but task is already holding lock: > > ffff888057ed9228 (&midi->transmit_lock){....}-{2:2}, at: > > f_midi_transmit+0x18c/0x1460 drivers/usb/gadget/function/f_midi.c:683 > > > > other info that might help us debug this: > > Possible unsafe locking scenario: > > > > CPU0 > > ---- > > lock(&midi->transmit_lock); > > lock(&midi->transmit_lock); > > > > *** DEADLOCK *** > > > > May be due to missing lock nesting notation > > That's a lockdep warning, is this really deadlocking? > > If so, I'd recommend asking the midi developers... > > thanks, > > greg k-h
