On Tue, Oct 2, 2018 at 6:04 PM, Shuah Khan <shuah@xxxxxxxxxx> wrote: > On 09/04/2018 12:52 PM, syzbot wrote: >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: 420f51f4ab6b Merge tag 'arm64-fixes' of git://git.kernel.o.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=126a6f0e400000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=531a917630d2a492 >> dashboard link: https://syzkaller.appspot.com/bug?extid=bccc1fe10b70fadc78d0 >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=121caa46400000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ed8ab6400000 > > C producer doesn't reproduce the problem on 4.19-rc5. Does this C producer > depend on state of the machine? i.e what is the status of vhci_hcd - are > there any devices attached? Hi Shuah, syzbot always runs tests reproducers on a clean machine. There is some state are running a Debian wheezy init, but no test/fuzz/stress workload is run before the reproducer. syzbot also uses VMs, so there are no real devices attached. And it's GCE VMs (not qemu), and I think GCE does not even emulate any USB devices. An obvious thing to try would be to use the exact commit and config syzbot gave (rather than 4.19-rc5). You can also take the image syzbot uses here: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#crash-does-not-reproduce > I can see the problem looking at the code and fix is easy. However, I would > like be able to reproduce it and verify the fix works. Also this would be a > good regression for the driver I could consider adding to selftests. syzbot can test fixes for bugs with reproducers: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches So it can test your fix. But this obviously won't help with a test.
