[PATCH v7 0/3] media: v4l2-subdev: Verify arguments in v4l2_subdev_call()

[Janusz Krzysztofik <jmkrzyszt@gmail.com>]

Correctness of format type (try or active) and pad ID parameters passed
to subdevice operation callbacks is now verified only for IOCTL calls.
However, those callbacks are also used by drivers, e.g., V4L2 host
interfaces.
    
Since both subdev_do_ioctl() and drivers are using v4l2_subdev_call()
macro while calling subdevice operations, move those parameter checks
from subdev_do_ioctl() to v4l2_subdev_call().  Also, add check for
non-NULL pointers, including pad config if V4L2_SUBDEV_FORMAT_TRY is
requested.

Having that done, we can avoid taking care of those checks inside
drivers.

Janusz Krzysztofik (3):
  media: v4l2-subdev: Verify arguments in v4l2_subdev_call()
  media: v4l2-subdev: Verify v4l2_subdev_call() pointer arguments
  media: v4l2-subdev: Verify v4l2_subdev_call() pad config argument

 drivers/media/v4l2-core/v4l2-subdev.c | 268 +++++++++++++++++---------
 include/media/v4l2-subdev.h           |   6 +
 2 files changed, 188 insertions(+), 86 deletions(-)

Changelog:
v6->v7:
Changes suggested by Sakari - thanks!
- never succeed pad check on media entities with pad_num == 0,
- allow pad 0 on subdevies not registered as media entities.

v5->v6:
- rename wrappers to call_something() as suggested by Sakari - thanks!
- make check_ functions inline - also on Sakari's suggestion, thanks!
- drop patch 2/4 and remove WARN_ONs from remaining patches to avoid
  kernel WARNs on non-kernel bugs - thanks Hans for pointing this out!

v4->v5:
- a few coding style and code formatting changes,
- require CONFIG_MEDIA_CONTROLLER, not CONFIG_VIDEO_V4L2_SUBDEV_API,
  for a valid pad ID check,
- perform pad ID check only if at least one pad is configured so
  drivers which don't configure pads are not affected if built with
  CONFIG_MEDIA_CONTROLLER defined,
- issue kernel warnings on invalid parameters (new patch - 2/4),
- validate pointers before using them (new patch - 3/4).

v3->v4:
- fix 'struct' keyword missing from patch 2/2,
- fix checkpatch reported style issue in patch 2/2
Sorry for that.

v2->v3:
- add patch 2/2 with pad config check,
- adjust continuation line alignments in patch 1/2 to match those
  used in 2/2.

v1->v2:
- replace the horrible macro with a structure of wrapper functions;
  inspired by Hans' and Sakari's comments - thanks!

-- 
2.21.0