media: venus: hfi: add check to handle incorrect queue size

commit 69baf245b2 upstream.

qsize represents size of shared queued between driver and video
firmware. Firmware can modify this value to an invalid large value. In
such situation, empty_space will be bigger than the space actually
available. Since new_wr_idx is not checked, so the following code will
result in an OOB write.
...
qsize = qhdr->q_size

if (wr_idx >= rd_idx)
 empty_space = qsize - (wr_idx - rd_idx)
....
if (new_wr_idx < qsize) {
 memcpy(wr_ptr, packet, dwords << 2) --> OOB write

Add check to ensure qsize is within the allocated size while
reading and writing packets into the queue.

Cc: stable@vger.kernel.org
Fixes: d96d3f30c0 ("[media] media: venus: hfi: add Venus HFI files")
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/media/platform/qcom/venus/hfi_venus.c

@@ -187,6 +187,9 @@ static int venus_write_queue(struct venus_hfi_device *hdev,
 	/* ensure rd/wr indices's are read from memory */
 	rmb();
 
+	if (qsize > IFACEQ_QUEUE_SIZE / 4)
+		return -EINVAL;
+
 	if (wr_idx >= rd_idx)
 		empty_space = qsize - (wr_idx - rd_idx);
 	else
@@ -255,6 +258,9 @@ static int venus_read_queue(struct venus_hfi_device *hdev,
 	wr_idx = qhdr->write_idx;
 	qsize = qhdr->q_size;
 
+	if (qsize > IFACEQ_QUEUE_SIZE / 4)
+		return -EINVAL;
+
 	/* make sure data is valid before using it */
 	rmb();