If a line is requested with debounce, and that results in debouncing
in software, and the line is subsequently reconfigured to enable edge
detection then the allocation of the kfifo to contain edge events is
overlooked.  This results in events being written to and read from an
uninitialised kfifo.  Read events are returned to userspace.

Initialise the kfifo in the case where the software debounce is
already active.

Fixes: 65cff7046406 ("gpiolib: cdev: support setting debounce")
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20240510065342.36191-1-warthog618@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

The use-after-free issue occurs as follows: when the GPIO chip device file
is being closed by invoking gpio_chrdev_release(), watched_lines is freed
by bitmap_free(), but the unregistration of lineinfo_changed_nb notifier
chain failed due to waiting write rwsem. Additionally, one of the GPIO
chip's lines is also in the release process and holds the notifier chain's
read rwsem. Consequently, a race condition leads to the use-after-free of
watched_lines.

Here is the typical stack when issue happened:

[free]
gpio_chrdev_release()
  --> bitmap_free(cdev->watched_lines)                  <-- freed
  --> blocking_notifier_chain_unregister()
    --> down_write(&nh->rwsem)                          <-- waiting rwsem
          --> __down_write_common()
            --> rwsem_down_write_slowpath()
                  --> schedule_preempt_disabled()
                    --> schedule()

[use]
st54spi_gpio_dev_release()
  --> gpio_free()
    --> gpiod_free()
      --> gpiod_free_commit()
        --> gpiod_line_state_notify()
          --> blocking_notifier_call_chain()
            --> down_read(&nh->rwsem);                  <-- held rwsem
            --> notifier_call_chain()
              --> lineinfo_changed_notify()
                --> test_bit(xxxx, cdev->watched_lines) <-- use after free

The side effect of the use-after-free issue is that a GPIO line event is
being generated for userspace where it shouldn't. However, since the chrdev
is being closed, userspace won't have the chance to read that event anyway.

To fix the issue, call the bitmap_free() function after the unregistration
of lineinfo_changed_nb notifier chain.

Fixes: 51c1064e82e7 ("gpiolib: add new ioctl() for monitoring changes in line info")
Signed-off-by: Zhongqiu Han <quic_zhonhan@quicinc.com>
Link: https://lore.kernel.org/r/20240505141156.2944912-1-quic_zhonhan@quicinc.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

We used a per-descriptor SRCU struct in order to not impose a wait with
synchronize_srcu() for descriptor X on read-only operations of
descriptor Y. Now that we no longer call synchronize_srcu() on
descriptor label change but only when releasing descriptor resources, we
can use a single SRCU structure for all GPIO descriptors in a given chip.

Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507172414.28513-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Commit 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
caused a massive drop in performance of requesting GPIO lines due to the
call to synchronize_srcu() on each label change. Rework the code to not
wait until all read-only users are done with reading the label but
instead atomically replace the label pointer and schedule its release
after all read-only critical sections are done.

To that end wrap the descriptor label in a struct that also contains the
rcu_head struct required for deferring tasks using call_srcu() and stop
using kstrdup_const() as we're required to allocate memory anyway. Just
allocate enough for the label string and rcu_head in one go.

Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/CAMRc=Mfig2oooDQYTqo23W3PXSdzhVO4p=G4+P8y1ppBOrkrJQ@mail.gmail.com/
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507121346.16969-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

intel-gpio for v6.9-2

* Make data pointer dereference robust in Intel Tangier driver

The following is an automated git shortlog grouped by driver:

tangier:
 -  Use correct type for the IRQ chip data

The controller has several register bits describing access control
information for a given GPIO pin. When SCR_SEC_[R|W]EN is unset, it
means we have full read/write access to all the registers for given GPIO
pin. When SCR_SEC[R|W]EN is set, it means we need to further check the
accompanying SCR_SEC_G1[R|W] bit to determine read/write access to all
the registers for given GPIO pin.

This check was previously declaring that a GPIO pin was accessible
only if either of the following conditions were met:

  - SCR_SEC_REN + SCR_SEC_WEN both set

    or

  - SCR_SEC_REN + SCR_SEC_WEN both set and
    SCR_SEC_G1R + SCR_SEC_G1W both set

Update the check to properly handle cases where only one of
SCR_SEC_REN or SCR_SEC_WEN is set.

Fixes: b2b56a163230 ("gpio: tegra186: Check GPIO pin permission before access.")
Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20240424095514.24397-1-pshete@nvidia.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

IRQ chip data contains a pointer to the GPIO chip. Luckily we have
the pointers the same, but strictly speaking it's not guaranteed.
Even though, still better to fix this.

Fixes: ccf6fd6dcc86 ("gpio: merrifield: Introduce GPIO driver to support Merrifield")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Add MODULE_DEVICE_TABLE(), so the module could be properly autoloaded
based on the alias from of_device_id table.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

intel-gpio for v6.9-1

* Fix returned code in the error path in Intel PMIC GPIO drivers

The following is an automated git shortlog grouped by driver:

crystalcove:
 -  Use -ENOTSUPP consistently

wcove:
 -  Use -ENOTSUPP consistently

The GPIO library expects the drivers to return -ENOTSUPP in some
cases and not using analogue POSIX code. Make the driver to follow
this.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>