i40e: force VMDQ device name truncation

In new versions of GCC since 7.x a new warning exists which warns when
a string is truncated before all of the format can be completed.

When we setup VMDQ netdev names we are copying a pre-existing interface
name which could be up to 15 characters in length. Since we also add
4 bytes, v, the literal %, the d and a \0 null, we would overrun the
available size unless snprintf truncated for us.

The snprintf call will of course truncate on the end, so lets instead
modify the code to force truncation of the copied netdev name by
4 characters, to create enough space for the 4 bytes we're adding.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26785018
(cherry picked from commit 8c9eb350aa7b66ab06f3e378dab3c7875a0bf83a)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Kyle Fortin <kyle.fortin@oracle.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index ddd8d070350ddd209a174e3b38189af04217d48f..a0bcd377039ac5dde8038de69b4c247e74eef0dc 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -9602,8 +9602,13 @@ static int i40e_config_netdev(struct i40e_vsi *vsi)
                i40e_add_mac_filter(vsi, mac_addr);
                spin_unlock_bh(&vsi->mac_filter_hash_lock);
        } else {
-               /* relate the VSI_VMDQ name to the VSI_MAIN name */
-               snprintf(netdev->name, IFNAMSIZ, "%sv%%d",
+               /* Relate the VSI_VMDQ name to the VSI_MAIN name. Note that we
+                * are still limited by IFNAMSIZ, but we're adding 'v%d\0' to
+                * the end, which is 4 bytes long, so force truncation of the
+                * original name by IFNAMSIZ - 4
+                */
+               snprintf(netdev->name, IFNAMSIZ, "%.*sv%%d",
+                        IFNAMSIZ - 4,
                         pf->vsi[pf->lan_vsi]->netdev->name);
                random_ether_addr(mac_addr);