linux-kernel - Re: [PATCH v2] efifb: prevent null-deref when iterating dmi

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Date:	Thu, 31 Oct 2013 17:17:54 +0100
From:	David Herrmann <dh.herrmann@...il.com>
To:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Cc:	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	James Bates <james.h.bates@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	James Bates <james.h.bates@...oo.com>
Subject: Re: [PATCH v2] efifb: prevent null-deref when iterating dmi_list

Hi

On Thu, Oct 31, 2013 at 11:45 AM, Jean-Christophe PLAGNIOL-VILLARD
<plagnioj@...osoft.com> wrote:
> On 18:40 Wed 02 Oct     , David Herrmann wrote:
>> The dmi_list array is initialized using gnu designated initializers, and
>> therefore may contain fewer explicitly defined entries as there are
>> elements in it. This is because the enum above with M_xyz constants
>> contains more items than the designated initializer. Those elements not
>> explicitly initialized are implicitly set to 0.
>>
>> Now efifb_setup() loops through all these array elements, and performs
>> a strcmp on each item. For non explicitly initialized elements this will
>> be a null pointer:
>>
>> This patch swaps the check order in the if statement, thus checks first
>> whether dmi_list[i].base is null.
>>
>> Signed-off-by: James Bates <james.h.bates@...oo.com>
>> Signed-off-by: David Herrmann <dh.herrmann@...il.com>
>
> with the simpleDRM arriving next merge I'm wondering if we need to keep it?

SimpleDRM is not coming next merge-window. It's basically finished,
but I'm still working on the user-space side as its KMS api is highly
reduced compared to fully-featured DRM/KMS drivers. Maybe 3.13 will
work out.

Anyhow, this patch is still needed as it fixes a serious bug for simplefb.

Thanks
David
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