linux-kernel - Re: [PATCH] HID: hidraw, fix a NULL pointer dereference in hidraw

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Message-ID: <4CA9DC8D.3030207@signal11.us>
Date:	Mon, 04 Oct 2010 09:54:21 -0400
From:	Alan Ott <alan@...nal11.us>
To:	Antonio Ospite <ospite@...denti.unina.it>
Cc:	linux-input@...r.kernel.org, Jiri Kosina <jkosina@...e.cz>,
	Oliver Neukum <oliver@...kum.name>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl

On 10/02/2010 07:25 AM, Antonio Ospite wrote:
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
> IP: [<ffffffffa02c66b4>] hidraw_ioctl+0xfc/0x32c [hid]
> [...]
>
> This is reproducible by disconnecting the device while userspace does ioctl in
> a loop and doesn't check return values in order to exit the loop
>
> Should this be applied to older stable kernels too?
>
>    
This doesn't have anything to do with my patch really, and goes way 
back. I'd say yes, to every stable kernel which is still being maintained.

> Alan, Jiri,
>
> there is a similar problem when _writing_ to the device, but Alan's
> changes in that area are shuffling the code a bit, should I send a patch
> [to hidraw_send_report()] on top of Alan's work for that, or a fix for
> current mainline [in hidraw_write()] on which Alan should rebase his
> work would be better?
>    

This needs to go back into stable kernels as well, so a patch against 
mainline will be necessary for that. If you want to make a patch against 
mine, that's fine with me. If you want me to work it into my patch, 
that's fine too. (I want you to get credit for the fix though :) ).

> The same pattern of unchecked hidraw_table[minor] is also present in
> hidraw_get_report but this function is called only after the NULL check
> in hidraw_ioctl _for_now_, so that is currently safe.
>    

I can stick a comment ahead of hidraw_send_report, similar to the one 
which already exists.

Alan.


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