[PATCH] net: am65-cpsw-nuss: fix out-of-bounds access

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

GCC 12.2.0 complains about am65_cpsw_recv:

drivers/net/am65-cpsw-nuss.c: In function ‘am65_cpsw_recv’:
drivers/net/am65-cpsw-nuss.c:495:30: warning: array subscript 9 is
  above array bounds of ‘struct am65_cpsw_port[9]’ [-Warray-bounds]
  495 |         port = &common->ports[port_id];
      |                 ~~~~~~~~~~~~~^~~~~~~~~
drivers/net/am65-cpsw-nuss.c:115:33: note: while referencing ‘ports’
  115 |         struct am65_cpsw_port  ports[AM65_CPSW_CPSWNU_MAX_PORTS];
      |                                 ^~~~~

port_id is read from the hardware and used unsanitized to index into an
array. Rework the code, so out-of-bound access leads to an error, but
no out of bound access.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/net/am65-cpsw-nuss.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/am65-cpsw-nuss.c b/drivers/net/am65-cpsw-nuss.c
index f6dc811bd982..6b9432e2d4e7 100644
--- a/drivers/net/am65-cpsw-nuss.c
+++ b/drivers/net/am65-cpsw-nuss.c
@@ -466,7 +466,6 @@ static void am65_cpsw_recv(struct eth_device *edev)
 	dma_addr_t pkt;
 	int ret;
 	u32 num, port_id;
-	bool valid = true;
 
 	if (!common->started)
 		return;
@@ -489,18 +488,17 @@ static void am65_cpsw_recv(struct eth_device *edev)
 	port_id = packet_data.src_tag;
 	if (port_id >= AM65_CPSW_CPSWNU_MAX_PORTS) {
 		dev_err(common->dev, "received pkt on invalid port_id %d\n", port_id);
-		valid = false;
+		goto out;
 	}
 
 	port = &common->ports[port_id];
 	if (!port->enabled) {
 		dev_err(common->dev, "received pkt on disabled port_id %d\n", port_id);
-		valid = false;
+		goto out;
 	}
 
-	if (valid)
-		net_receive(&port->edev, (void *)pkt, ret);
-
+	net_receive(&port->edev, (void *)pkt, ret);
+out:
 	num = common->rx_next % UDMA_RX_DESC_NUM;
 
 	dma_sync_single_for_device(common->dev, pkt, ret, DMA_FROM_DEVICE);
-- 
2.39.5