[PATCH 3/4] media: venus: hfi: add check to handle incorrect queue size

[Vikash Garodia <quic_vgarodia@quicinc.com>]

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: d96d3f30c0f2 ("[media] media: venus: hfi: add Venus HFI files")
Signed-off-by: Vikash Garodia <quic_vgarodia@quicinc.com>
---
 drivers/media/platform/qcom/venus/hfi_venus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/platform/qcom/venus/hfi_venus.c b/drivers/media/platform/qcom/venus/hfi_venus.c
index f9437b6412b91c2483670a2b11f4fd43f3206404..50d92214190d88eff273a5ba3f95486f758bcc05 100644
--- a/drivers/media/platform/qcom/venus/hfi_venus.c
+++ b/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();
 

-- 
2.34.1