linux-kernel - [PATCH] media: v4l2-dev: Check that g/s_selection are valid before selecting crop

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Date:   Tue,  7 Nov 2023 21:05:09 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Hans Verkuil <hverkuil@...all.nl>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: [PATCH] media: v4l2-dev: Check that g/s_selection are valid before selecting crop

The cropcap and g/s_crop ioctls are automatically marked as valid whenever the
g/s_selection ops are filled. The rationale is to auto-enable these legacy
cropcap and g/s_crop ioctls that rely on g/s_selection.

However it's possible that the ops are filled but explicitly disabled with
calls to v4l2_disable_ioctl. In this situation the legacy ioctls should not
be enabled.

Add a check on the video device's valid ioctls field before auto-selecting
them to honor the driver's choice. Note that the meaning of the bitfield
stored in the video device is the opposite of what the name suggests as
v4l2_disable_ioctl will set the bits. Their meaning will be reversed at
the end of the function.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
---
 drivers/media/v4l2-core/v4l2-dev.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index f81279492682..d13954bd31fd 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -642,11 +642,13 @@ static void determine_valid_ioctls(struct video_device *vdev)
 		SET_VALID_IOCTL(ops, VIDIOC_TRY_DECODER_CMD, vidioc_try_decoder_cmd);
 		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMESIZES, vidioc_enum_framesizes);
 		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMEINTERVALS, vidioc_enum_frameintervals);
-		if (ops->vidioc_g_selection) {
+		if (ops->vidioc_g_selection &&
+		    !test_bit(_IOC_NR(VIDIOC_G_SELECTION), vdev->valid_ioctls)) {
 			__set_bit(_IOC_NR(VIDIOC_G_CROP), valid_ioctls);
 			__set_bit(_IOC_NR(VIDIOC_CROPCAP), valid_ioctls);
 		}
-		if (ops->vidioc_s_selection)
+		if (ops->vidioc_s_selection &&
+		    !test_bit(_IOC_NR(VIDIOC_S_SELECTION), vdev->valid_ioctls))
 			__set_bit(_IOC_NR(VIDIOC_S_CROP), valid_ioctls);
 		SET_VALID_IOCTL(ops, VIDIOC_G_SELECTION, vidioc_g_selection);
 		SET_VALID_IOCTL(ops, VIDIOC_S_SELECTION, vidioc_s_selection);
-- 
2.42.0