Re: [PATCH v3 0/2] gpiolib: don't allow user-space to crash the kernel with hot-unplugs

[Andy Shevchenko]

On Tue, Nov 29, 2022 at 01:35:51PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> 
> This is a second iteration of the changes that aim at fixing the situation
> in which the user-space can provoke a NULL-pointer derefence in the kernel
> when a GPIO device that's in use by user-space is removed.
> 
> I didn't add the review tags as the code changes significantly.

LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

Some nit-picks are in the individual reply(ies).

> v2 -> v3:
> - drop the helper variable in patch 1/2 as we won't be using it in 2/2
> - refactor patch 2/2 to use locking wrappers around the syscall callbacks
> 
> v1 -> v2:
> - add missing gdev->chip checks in patch 1/2
> - add a second patch that protects the structures that can be accessed
>   by user-space calls against concurrent removal
> 
> Bartosz Golaszewski (2):
>   gpiolib: cdev: fix NULL-pointer dereferences
>   gpiolib: protect the GPIO device against being dropped while in use by
>     user-space
> 
>  drivers/gpio/gpiolib-cdev.c | 190 +++++++++++++++++++++++++++++++-----
>  drivers/gpio/gpiolib.c      |   3 +
>  drivers/gpio/gpiolib.h      |   5 +
>  3 files changed, 176 insertions(+), 22 deletions(-)
> 
> -- 
> 2.37.2
> 

-- 
With Best Regards,
Andy Shevchenko