net: stmmac: fix gcc-10 -Wrestrict warning

gcc-10 and later warn about a theoretical array overrun when
accessing priv->int_name_rx_irq[i] with an out of bounds value
of 'i':

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c: In function 'stmmac_request_irq_multi_msi':
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:3528:17: error: 'snprintf' argument 4 may overlap destination object 'dev' [-Werror=restrict]
 3528 |                 snprintf(int_name, int_name_len, "%s:%s-%d", dev->name, "tx", i);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:3404:60: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
 3404 | static int stmmac_request_irq_multi_msi(struct net_device *dev)
      |                                         ~~~~~~~~~~~~~~~~~~~^~~

The warning is a bit strange since it's not actually about the array
bounds but rather about possible string operations with overlapping
arguments, but it's not technically wrong.

Avoid the warning by adding an extra bounds check.

Fixes: 8532f613bc78 ("net: stmmac: introduce MSI Interrupt routines for mac, safety, RX & TX")
Link: https://lore.kernel.org/all/20210421134743.3260921-1-arnd@kernel.org/
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 553c4403258aa2c30cb2ca06f30f2db69efc6f3f..640c0ffdff3d25ecfce7737117245398271ced68 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3502,6 +3502,8 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
 
        /* Request Rx MSI irq */
        for (i = 0; i < priv->plat->rx_queues_to_use; i++) {
+               if (i > MTL_MAX_RX_QUEUES)
+                       break;
                if (priv->rx_irq[i] == 0)
                        continue;
 
@@ -3525,6 +3527,8 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
 
        /* Request Tx MSI irq */
        for (i = 0; i < priv->plat->tx_queues_to_use; i++) {
+               if (i > MTL_MAX_TX_QUEUES)
+                       break;
                if (priv->tx_irq[i] == 0)
                        continue;