[PATCH] drivers: avoid use after free of a pinctrl context pointer

[PATCH] drivers: avoid use after free of a pinctrl context pointer

[Guennadi Liakhovetski]

During probing, pinctrl context is allocated and assigned to the struct
device::pins pointer. If probing fails or if the driver is later unbound
and re-probed again, the memory is freed, but the pointer is not cleared.
On a repeated probing attempt a non-NULL pointer indicates an already
allocated context, which then gets used. To avoid this the pointer must
be cleared.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---
 drivers/base/dd.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 65631015..e5c71b5 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -302,6 +302,7 @@ probe_failed:
 	devres_release_all(dev);
 	driver_sysfs_remove(dev);
 	dev->driver = NULL;
+	dev->pins = NULL;
 	dev_set_drvdata(dev, NULL);
 
 	if (ret == -EPROBE_DEFER) {
@@ -505,6 +506,7 @@ static void __device_release_driver(struct device *dev)
 			drv->remove(dev);
 		devres_release_all(dev);
 		dev->driver = NULL;
+		dev->pins = NULL;
 		dev_set_drvdata(dev, NULL);
 		klist_remove(&dev->p->knode_driver);
 		if (dev->bus)
-- 
1.7.2.5

Re: [PATCH] drivers: avoid use after free of a pinctrl context pointer

[Greg Kroah-Hartman]

On Wed, Jan 16, 2013 at 05:22:34PM +0100, Guennadi Liakhovetski wrote:
> During probing, pinctrl context is allocated and assigned to the struct
> device::pins pointer. If probing fails or if the driver is later unbound
> and re-probed again, the memory is freed, but the pointer is not cleared.
> On a repeated probing attempt a non-NULL pointer indicates an already
> allocated context, which then gets used. To avoid this the pointer must
> be cleared.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> ---
>  drivers/base/dd.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)

This can't go through my tree, as it breaks the build.  Please send it
to whereever the pinctrl code is coming from.

thanks,

greg k-h