nfp: protect from theoretical size overflows on HW descriptor ring

Use array_size() and store the size as full size_t to protect from
theoretical size overflow when handling HW descriptor rings.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net.h

@@ -250,7 +250,7 @@ struct nfp_net_tx_ring {
 	struct nfp_net_tx_desc *txds;
 
 	dma_addr_t dma;
-	unsigned int size;
+	size_t size;
 	bool is_xdp;
 } ____cacheline_aligned;
 
@@ -372,7 +372,7 @@ struct nfp_net_rx_ring {
 	struct xdp_rxq_info xdp_rxq;
 
 	dma_addr_t dma;
-	unsigned int size;
+	size_t size;
 } ____cacheline_aligned;
 
 /**

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -54,6 +54,7 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/mm.h>
+#include <linux/overflow.h>
 #include <linux/page_ref.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
@@ -1121,7 +1122,7 @@ nfp_net_tx_ring_reset(struct nfp_net_dp *dp, struct nfp_net_tx_ring *tx_ring)
 		tx_ring->rd_p++;
 	}
 
-	memset(tx_ring->txds, 0, sizeof(*tx_ring->txds) * tx_ring->cnt);
+	memset(tx_ring->txds, 0, tx_ring->size);
 	tx_ring->wr_p = 0;
 	tx_ring->rd_p = 0;
 	tx_ring->qcp_rd_p = 0;
@@ -1301,7 +1302,7 @@ static void nfp_net_rx_ring_reset(struct nfp_net_rx_ring *rx_ring)
 	rx_ring->rxbufs[last_idx].dma_addr = 0;
 	rx_ring->rxbufs[last_idx].frag = NULL;
 
-	memset(rx_ring->rxds, 0, sizeof(*rx_ring->rxds) * rx_ring->cnt);
+	memset(rx_ring->rxds, 0, rx_ring->size);
 	rx_ring->wr_p = 0;
 	rx_ring->rd_p = 0;
 }
@@ -2154,7 +2155,7 @@ nfp_net_tx_ring_alloc(struct nfp_net_dp *dp, struct nfp_net_tx_ring *tx_ring)
 
 	tx_ring->cnt = dp->txd_cnt;
 
-	tx_ring->size = sizeof(*tx_ring->txds) * tx_ring->cnt;
+	tx_ring->size = array_size(tx_ring->cnt, sizeof(*tx_ring->txds));
 	tx_ring->txds = dma_zalloc_coherent(dp->dev, tx_ring->size,
 					    &tx_ring->dma, GFP_KERNEL);
 	if (!tx_ring->txds)
@@ -2308,7 +2309,7 @@ nfp_net_rx_ring_alloc(struct nfp_net_dp *dp, struct nfp_net_rx_ring *rx_ring)
 	}
 
 	rx_ring->cnt = dp->rxd_cnt;
-	rx_ring->size = sizeof(*rx_ring->rxds) * rx_ring->cnt;
+	rx_ring->size = array_size(rx_ring->cnt, sizeof(*rx_ring->rxds));
 	rx_ring->rxds = dma_zalloc_coherent(dp->dev, rx_ring->size,
 					    &rx_ring->dma, GFP_KERNEL);
 	if (!rx_ring->rxds)