linux-kernel - Re: [RESEND PATCH] module param_call: fix potential NULL pointer dereference

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Date:	Tue, 23 Feb 2010 12:37:42 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Dongdong Deng <dongdong.deng@...driver.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RESEND PATCH] module param_call: fix potential NULL pointer 
	dereference

On Tue, Feb 23, 2010 at 11:56 AM, Rusty Russell <rusty@...tcorp.com.au> wrote:
> On Mon, 22 Feb 2010 09:10:51 pm Dongdong Deng wrote:
>> The param_set_fn() function will get a parameter which is a NULL
>> pointer when insmod module via bare params as following method:
>>
>> $insmod foo.ko foo
>>
>> If the param_set_fn() function didn't check that parameter and used
>> it directly, it could caused an OOPS due to NULL pointer dereference.
>>
>> The solution is simple:
>> Using "" to replace NULL parameter, thereby the param_set_fn()
>> function will never get a NULL pointer.
>
> This changes the value of booleans, and loses checking for int params, etc.
>
> I liked Americo's approach; I've combined the two approaches below.
>
> Since I'm going away, can Andrew take this?
>
> Subject: params: don't hand NULL values to param.set callbacks.
>
> An audit by Dongdong Deng revealed that most driver-author-written param
> calls don't handle val == NULL (which happens when parameters are specified
> with no =, eg "foo" instead of "foo=1").
>
> The only real case to use this is boolean, so handle it specially for that
> case and remove a source of bugs for everyone else as suggested by Americo.
>

Yeah, thanks, this one looks better than mine.

Acked-by: WANG Cong <xiyou.wangcong@...il.com>
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