Re: [PATCH] mtd: nand: mxc_nand: fix a possible NULL dereference

From: Frans Klaver
Date: Thu Nov 12 2015 - 03:37:02 EST

On Thu, Nov 12, 2015 at 9:26 AM, Uwe Kleine-KÃnig
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
> On Thu, Nov 12, 2015 at 09:03:11AM +0100, Frans Klaver wrote:
>> Hi,
>> On Thu, Nov 12, 2015 at 8:46 AM, LABBE Corentin
>> <clabbe.montjoie@xxxxxxxxx> wrote:
>> > of_match_device could return NULL, and so cause a NULL pointer
>> > dereference later.
>> Did you actually run into this? It seems to me that this driver is
>> only probed if and only if we have a match and that therefore
>> of_match_device will always return a valid pointer (it is using the
>> same match table). Am I missing something?
> Yes, you're missing something. The driver would probe for a dt snippet
> like:
> mxc_nand {
> compatible = "foobar";
> }
> In this case dev->of_node is non-NULL but of_match_device(mxcnd_dt_ids,
> dev) is.
> (I didn't actually test this, so there is a chance I'm wrong here. And
> if not I wonder if it is sensible at all to match the device name on
> driver name for of-created platform devices.)

Yea, looks like you're right. platform devices check a number of
things to determine a match, among which is driver name if all else
fails (platform.c, platform_match()).

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