[PATCH v4 0/2] gpiolib: don't allow user-space to crash the kernel with hot-unplugs

From: Bartosz Golaszewski
Date: Wed Nov 30 2022 - 04:06:06 EST


From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>

Sending it once more with some more tweaks and review tags collected. Will
apply shortly.

--

This is 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.

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 | 190 +++++++++++++++++++++++++++++++-----
drivers/gpio/gpiolib.c | 4 +
drivers/gpio/gpiolib.h | 5 +
3 files changed, 177 insertions(+), 22 deletions(-)

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2.37.2