linux-kernel - Re: [PATCH v2 4/5] firmware: actually return NULL on failed request_firmware

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Message-ID: <20151221190609.GP20409@wotan.suse.de>
Date:	Mon, 21 Dec 2015 20:06:10 +0100
From:	"Luis R. Rodriguez" <mcgrof@...e.com>
To:	Brian Norris <computersforpeace@...il.com>
Cc:	Shuah Khan <shuahkh@....samsung.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ming Lei <ming.lei@...onical.com>,
	Kees Cook <keescook@...omium.org>,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH v2 4/5] firmware: actually return NULL on failed
 request_firmware_nowait()

On Wed, Dec 09, 2015 at 02:50:28PM -0800, Brian Norris wrote:
> The kerneldoc for request_firmware_nowait() says that it may call the
> provided cont() callback with @fw == NULL, if the firmware request
> fails. However, this is not the case when called with an empty string
> (""). This case is short-circuited by the 'name[0] == '\0'' check
> introduced in commit 471b095dfe0d ("firmware_class: make sure fw requests
> contain a name"), so _request_firmware() never gets to set the fw to
> NULL.
> 
> Noticed while using the new 'trigger_async_request' testing hook:

<-- snip -->

> 
>     # printf '\x00' > /sys/devices/virtual/misc/test_firmware/trigger_async_request
>     [   32.126322] test_firmware: loading ''
>     [   32.129995] test_firmware: failed to async load firmware
>     -bash: printf: write error: No such device
> 
> Fixes: 471b095dfe0d ("firmware_class: make sure fw requests contain a name")
> Signed-off-by: Brian Norris <computersforpeace@...il.com>
> Acked-by: Ming Lei <ming.lei@...onical.com>
> Acked-by: Kees Cook <keescook@...omium.org>

Acked-by: Luis R. Rodriguez <mcgrof@...e.com>

  Luis
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