linux-kernel - Re: KASAN: slab-out-of-bounds Read in gadget_dev_desc_UDC

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Date:   Fri, 1 May 2020 09:05:38 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Kyungtae Kim <kt0755@...il.com>
Cc:     balbi@...nel.org, syzkaller <syzkaller@...glegroups.com>,
        USB list <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Dave Tian <dave.jing.tian@...il.com>
Subject: Re: KASAN: slab-out-of-bounds Read in gadget_dev_desc_UDC_store

On Thu, Apr 30, 2020 at 11:03:54PM -0400, Kyungtae Kim wrote:
> We report a bug (in linux-5.6.8) found by FuzzUSB (a modified version
> of syzkaller).
> 
> This happened when the size of "name" buffer is smaller than that of
> "page" buffer
> (after function kstrdup executed at line 263).
> I guess it comes from the "page" buffer containing 0 value in the middle.
> So accessing the "name" buffer with "len" variable, which is used to
> indicate the size of "page" buffer,
> triggered memory access violation.
> To fix, it may need to check the size of name buffer, and try to use
> right index variable.

Can you submit a patch for this as you have a reproducer to test the
issue?

thanks,

greg k-h