mbox series

[v6,0/2] gpiolib: don't allow user-space to crash the kernel with hot-unplugs

Message ID 20221201125928.3031325-1-brgl@bgdev.pl
Headers
Series gpiolib: don't allow user-space to crash the kernel with hot-unplugs |

Message

Bartosz Golaszewski Dec. 1, 2022, 12:59 p.m. UTC 
  From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

This is (hopefully) the final 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.

v5 -> v6:
- signal an error in poll callbacks instead of returning 0 which would make
  the user-space assume a timeout occurred (which could lead to user-space
  spinning a timeout loop forever)

v4 -> v5:
- try to acquire the semaphore for reading and bail out of syscall callbacks
  immediately in case of lock contention

v3 -> v4:
- use function typedefs to make code cleaner
- add a blank line after down_write()

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 | 193 ++++++++++++++++++++++++++++++++----
 drivers/gpio/gpiolib.c      |   4 +
 drivers/gpio/gpiolib.h      |   5 +
 3 files changed, 180 insertions(+), 22 deletions(-)

Comments

Andy Shevchenko Dec. 1, 2022, 1:59 p.m. UTC | #1 
On Thu, Dec 01, 2022 at 02:00:06PM +0100, Bartosz Golaszewski wrote:
> On Thu, Dec 1, 2022 at 1:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:

...

> I know Kent and Linus left their review tags already, I will add them
> when applying.

I guess it's good enough, go ahead with it.
Bartosz Golaszewski Dec. 1, 2022, 2:13 p.m. UTC | #2 
On Thu, Dec 1, 2022 at 2:59 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Dec 01, 2022 at 02:00:06PM +0100, Bartosz Golaszewski wrote:
> > On Thu, Dec 1, 2022 at 1:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> ...
>
> > I know Kent and Linus left their review tags already, I will add them
> > when applying.
>
> I guess it's good enough, go ahead with it.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Can you leave your Reviewed-by here too?

Bart
Andy Shevchenko Dec. 1, 2022, 3:40 p.m. UTC | #3 
On Thu, Dec 01, 2022 at 03:13:55PM +0100, Bartosz Golaszewski wrote:
> On Thu, Dec 1, 2022 at 2:59 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > On Thu, Dec 01, 2022 at 02:00:06PM +0100, Bartosz Golaszewski wrote:
> > > On Thu, Dec 1, 2022 at 1:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> >
> > ...
> >
> > > I know Kent and Linus left their review tags already, I will add them
> > > when applying.
> >
> > I guess it's good enough, go ahead with it.
> 
> Can you leave your Reviewed-by here too?

Hmm... Your both patches already have it.
Bartosz Golaszewski Dec. 1, 2022, 6:15 p.m. UTC | #4 
On Thu, Dec 1, 2022 at 4:40 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Dec 01, 2022 at 03:13:55PM +0100, Bartosz Golaszewski wrote:
> > On Thu, Dec 1, 2022 at 2:59 PM Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> > >
> > > On Thu, Dec 01, 2022 at 02:00:06PM +0100, Bartosz Golaszewski wrote:
> > > > On Thu, Dec 1, 2022 at 1:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > >
> > > ...
> > >
> > > > I know Kent and Linus left their review tags already, I will add them
> > > > when applying.
> > >
> > > I guess it's good enough, go ahead with it.
> >
> > Can you leave your Reviewed-by here too?
>
> Hmm... Your both patches already have it.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

I was thinking about the mailing list's history but whatever. Applying it now.

Bart