[PATCH V2 net 1/3] net: ena: Fix undefined state when tx request id is out of bounds

[Arthur Kiyanovski <akiyano@amazon.com>]

ena_com_tx_comp_req_id_get() checks the req_id of a received completion,
and if it is out of bounds returns -EINVAL. This is a sign that
something is wrong with the device and it needs to be reset.

The current code does not reset the device in this case, which leaves
the driver in an undefined state, where this completion is not properly
handled.

This commit adds a call to handle_invalid_req_id() in ena_clean_tx_irq()
and ena_clean_xdp_irq() which resets the device to fix the issue.

This commit also removes unnecessary request id checks from
validate_tx_req_id() and validate_xdp_req_id(). This check is unneeded
because it was already performed in ena_com_tx_comp_req_id_get(), which
is called right before these functions.

Fixes: 548c4940b9f1 ("net: ena: Implement XDP_TX action")
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 34 ++++++++++++--------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 7d5d885d85d5..2274063e34cc 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1288,26 +1288,22 @@ static int handle_invalid_req_id(struct ena_ring *ring, u16 req_id,
 
 static int validate_tx_req_id(struct ena_ring *tx_ring, u16 req_id)
 {
-	struct ena_tx_buffer *tx_info = NULL;
+	struct ena_tx_buffer *tx_info;
 
-	if (likely(req_id < tx_ring->ring_size)) {
-		tx_info = &tx_ring->tx_buffer_info[req_id];
-		if (likely(tx_info->skb))
-			return 0;
-	}
+	tx_info = &tx_ring->tx_buffer_info[req_id];
+	if (likely(tx_info->skb))
+		return 0;
 
 	return handle_invalid_req_id(tx_ring, req_id, tx_info, false);
 }
 
 static int validate_xdp_req_id(struct ena_ring *xdp_ring, u16 req_id)
 {
-	struct ena_tx_buffer *tx_info = NULL;
+	struct ena_tx_buffer *tx_info;
 
-	if (likely(req_id < xdp_ring->ring_size)) {
-		tx_info = &xdp_ring->tx_buffer_info[req_id];
-		if (likely(tx_info->xdpf))
-			return 0;
-	}
+	tx_info = &xdp_ring->tx_buffer_info[req_id];
+	if (likely(tx_info->xdpf))
+		return 0;
 
 	return handle_invalid_req_id(xdp_ring, req_id, tx_info, true);
 }
@@ -1332,9 +1328,14 @@ static int ena_clean_tx_irq(struct ena_ring *tx_ring, u32 budget)
 
 		rc = ena_com_tx_comp_req_id_get(tx_ring->ena_com_io_cq,
 						&req_id);
-		if (rc)
+		if (rc) {
+			if (unlikely(rc == -EINVAL))
+				handle_invalid_req_id(tx_ring, req_id, NULL,
+						      false);
 			break;
+		}
 
+		/* validate that the request id points to a valid skb */
 		rc = validate_tx_req_id(tx_ring, req_id);
 		if (rc)
 			break;
@@ -1896,9 +1897,14 @@ static int ena_clean_xdp_irq(struct ena_ring *xdp_ring, u32 budget)
 
 		rc = ena_com_tx_comp_req_id_get(xdp_ring->ena_com_io_cq,
 						&req_id);
-		if (rc)
+		if (rc) {
+			if (unlikely(rc == -EINVAL))
+				handle_invalid_req_id(xdp_ring, req_id, NULL,
+						      true);
 			break;
+		}
 
+		/* validate that the request id points to a valid xdp_frame */
 		rc = validate_xdp_req_id(xdp_ring, req_id);
 		if (rc)
 			break;
-- 
2.32.0