linux-kernel - [PATCH 5.10 136/593] media: cedrus: Fix .buf

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Date:   Mon, 12 Jul 2021 08:04:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 136/593] media: cedrus: Fix .buf_prepare

From: Andrzej Pietrasiewicz <andrzej.p@...labora.com>

[ Upstream commit d84b9202d712309840f8b5abee0ed272506563bd ]

The driver should only set the payload on .buf_prepare if the
buffer is CAPTURE type. If an OUTPUT buffer has a zero bytesused
set by userspace then v4l2-core will set it to buffer length.

If we overwrite bytesused for OUTPUT buffers, too, then
vb2_get_plane_payload() will return incorrect value which might be then
written to hw registers by the driver in cedrus_h264.c or cedrus_vp8.c.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/staging/media/sunxi/cedrus/cedrus_video.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
index 911f607d9b09..16327be904d1 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
@@ -449,7 +449,13 @@ static int cedrus_buf_prepare(struct vb2_buffer *vb)
 	if (vb2_plane_size(vb, 0) < pix_fmt->sizeimage)
 		return -EINVAL;
 
-	vb2_set_plane_payload(vb, 0, pix_fmt->sizeimage);
+	/*
+	 * Buffer's bytesused must be written by driver for CAPTURE buffers.
+	 * (for OUTPUT buffers, if userspace passes 0 bytesused, v4l2-core sets
+	 * it to buffer length).
+	 */
+	if (V4L2_TYPE_IS_CAPTURE(vq->type))
+		vb2_set_plane_payload(vb, 0, pix_fmt->sizeimage);
 
 	return 0;
 }
-- 
2.30.2