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Date:   Fri, 3 Jun 2022 14:04:04 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     syzbot <syzbot+dd3c97de244683533381@syzkaller.appspotmail.com>
Cc:     gregkh@linuxfoundation.org, hdanton@sina.com, lenb@kernel.org,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        rafael.j.wysocki@intel.com, rafael@kernel.org, rjw@rjwysocki.net,
        syzkaller-bugs@googlegroups.com, linux-usb@vger.kernel.org,
        Alan Stern <stern@rowland.harvard.edu>
Subject: Re: [syzbot] general protection fault in __device_attach
Message-ID: <YpnqpMYcokTwCB6u@smile.fi.intel.com>
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 <00000000000010b7d305e08837c8@google.com>
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On Fri, Jun 03, 2022 at 03:02:07AM -0700, syzbot wrote:
> syzbot has bisected this issue to:
> 
> commit a9c4cf299f5f79d5016c8a9646fa1fc49381a8c1
> Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Date:   Fri Jun 18 13:41:27 2021 +0000
> 
>     ACPI: sysfs: Use __ATTR_RO() and __ATTR_RW() macros

Hmm... It's not obvious at all how this change can alter the behaviour so
drastically. device_add() is called from USB core with intf->dev.name == NULL
by some reason. A-ha, seems like fault injector, which looks like

	dev_set_name(&intf->dev, "%d-%s:%d.%d", dev->bus->busnum,
		     dev->devpath, configuration, ifnum);

missed the return code check.

But I'm not familiar with that code at all, adding Linux USB ML and Alan.

> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1040b80df00000
> start commit:   d1dc87763f40 assoc_array: Fix BUG_ON during garbage collect
> git tree:       upstream
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=1240b80df00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1440b80df00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c51cd24814bb5665
> dashboard link: https://syzkaller.appspot.com/bug?extid=dd3c97de244683533381
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15613e2bf00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c90adbf00000
> 
> Reported-by: syzbot+dd3c97de244683533381@syzkaller.appspotmail.com
> Fixes: a9c4cf299f5f ("ACPI: sysfs: Use __ATTR_RO() and __ATTR_RW() macros")
> 
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

-- 
With Best Regards,
Andy Shevchenko