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Date: Mon, 12 Dec 2016 16:05:43 -0500 (EST)
From: Alan Stern <stern@rowland.harvard.edu>
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To: Andrey Konovalov <andreyknvl@google.com>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        USB list <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>, Kostya Serebryany <kcc@google.com>,
        syzkaller <syzkaller@googlegroups.com>
Subject: Re: usb/core: warning in usb_create_ep_devs/sysfs_create_dir_ns
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On Mon, 12 Dec 2016, Andrey Konovalov wrote:

> Hi!
> 
> While running the syzkaller fuzzer I've got the following error report.
> 
> On commit 3c49de52d5647cda8b42c4255cf8a29d1e22eff5 (Dev 2).
> 
> WARNING: CPU: 2 PID: 865 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x8a/0xa0
> gadgetfs: disconnected
> sysfs: cannot create duplicate filename
> '/devices/platform/dummy_hcd.0/usb2/2-1/2-1:64.0/ep_05'
> Kernel panic - not syncing: panic_on_warn set ...

I suppose we could check for USB devices that claim to have two 
endpoints with the same address.  But is it really worthwhile?  A 
kernel warning isn't so bad when you're dealing with buggy device 
firmware.

Alan Stern