[PATCH 6.4 507/737] media: mediatek: vcodec: fix potential double free

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6.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit be40f524b6edac4fb9a98ef79620fd9b9497a998 ]

The "lat_buf->private_data" needs to be set to NULL to prevent a
double free.  How this would happen is if vdec_msg_queue_init() failed
twice in a row and on the second time it failed earlier than on the
first time.

The vdec_msg_queue_init() function has a loop which does:
	for (i = 0; i < NUM_BUFFER_COUNT; i++) {

Each iteration initializes one element in the msg_queue->lat_buf[] array
and then the clean up function vdec_msg_queue_deinit() frees each
element of the msg_queue->lat_buf[] array.  This clean up code relies
on the assumption that every element is either initialized or zeroed.
Leaving a freed pointer which is non-zero breaks the assumption.

Fixes: b199fe46f35c ("media: mtk-vcodec: Add msg queue feature for lat and core architecture")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/media/platform/mediatek/vcodec/vdec_msg_queue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/platform/mediatek/vcodec/vdec_msg_queue.c b/drivers/media/platform/mediatek/vcodec/vdec_msg_queue.c
index 03f8d7cd8eddc..675f62814f94e 100644
--- a/drivers/media/platform/mediatek/vcodec/vdec_msg_queue.c
+++ b/drivers/media/platform/mediatek/vcodec/vdec_msg_queue.c
@@ -246,6 +246,7 @@ void vdec_msg_queue_deinit(struct vdec_msg_queue *msg_queue,
 			mtk_vcodec_mem_free(ctx, mem);
 
 		kfree(lat_buf->private_data);
+		lat_buf->private_data = NULL;
 	}
 }
 
-- 
2.40.1






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