On Wed, 7 Aug 2019, Oliver Neukum wrote: > Am Dienstag, den 06.08.2019, 15:13 -0400 schrieb Alan Stern: > > On Thu, 1 Aug 2019, syzbot wrote: > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 7f7867ff usb-fuzzer: main usb gadget fuzzer driver > > > git tree: https://github.com/google/kasan.git usb-fuzzer > > > console output: https://syzkaller.appspot.com/x/log.txt?x=136b6aec600000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=792eb47789f57810 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=7bbcbe9c9ff0cd49592a > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+7bbcbe9c9ff0cd49592a@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > ====================================================== > > > WARNING: possible circular locking dependency detected > > > 5.3.0-rc2+ #23 Not tainted > > > ------------------------------------------------------ > > > > Andrey: > > > > This should be completely reproducible, since it's a simple ABBA > > locking violation. Maybe just introducing a time delay (to avoid races > > and give the open() call time to run) between the gadget creation and > > gadget removal would be enough to do it. > > Hi, > > technically yes. However in practical terms the straight revert I sent > out yesterday should fix it. I didn't see the revert, and it doesn't appear to have reached the mailing list archive. Can you post it again? Alan Stern PS: syzbot reported a similar lock inversion problem (involving two mutexes rather than just one) in drivers/usb/misc/iowarrior.c. Probably the two drivers need similar fixes.
