Messages in this thread Patch in this message | | | Date | Thu, 12 Nov 2015 09:53:12 +0100 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] mtd: nand: mxc_nand: fix a possible NULL dereference |
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CC += devicetree@vger.kernel.org, gregkh
On Thu, Nov 12, 2015 at 09:36:55AM +0100, Frans Klaver wrote: > On Thu, Nov 12, 2015 at 9:26 AM, Uwe Kleine-König > <u.kleine-koenig@pengutronix.de> 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@gmail.com> 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()).
Maybe something like this would help to reduce surprises:
diff --git a/drivers/base/platform.c b/drivers/base/platform.c index f80aaaf9f610..a9fc22c86552 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -840,8 +840,8 @@ static int platform_match(struct device *dev, struct device_driver *drv) return !strcmp(pdev->driver_override, drv->name); /* Attempt an OF style match first */ - if (of_driver_match_device(dev, drv)) - return 1; + if (pdev->dev.of_node) + return of_driver_match_device(dev, drv); /* Then try ACPI style match */ if (acpi_driver_match_device(dev, drv)) Maybe something similar for acpi devices is desirable, too?
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
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