opal/util/ethtool.c: fix interface name len

Per a comment in opal/util/if.h, we hard-code OPAL_IF_NAMESIZE to 32 --
regardless of what the underlying IF_NAMESIZE is.  On some Linux
systems, IF_NAMESIZE if 16, leading to a potential memory overrun when
we copy the interface name.  In practice, this probably wouldn't
happen because we use opal_string_copy(), which will only copy up to
the terminating \0, and Linux network interface names will always have
a terminating \0.

But we might as well be defensive, and use the underlying IF_NAMESIZE
(this file already includes <net/if.h>, where that should be defined).

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

opal/util/ethtool.c

@@ -2,7 +2,7 @@
  * Copyright (c) 2016      Karol Mroz.  All rights reserved.
  * Copyright (c) 2016      Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
- * Copyright (c) 2016      Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2016-2022 Cisco Systems, Inc.  All rights reserved.
  * $COPYRIGHT$
  *
  * Additional copyrights may follow
@@ -63,7 +63,7 @@ unsigned int opal_ethtool_get_speed(const char *if_name)
     }
 
     memset(&ifr, 0, sizeof(struct ifreq));
-    opal_string_copy(ifr.ifr_name, if_name, OPAL_IF_NAMESIZE);
+    opal_string_copy(ifr.ifr_name, if_name, IF_NAMESIZE);
     ifr.ifr_data = (char *) &edata;
 
     if (ioctl(sockfd, SIOCETHTOOL, &ifr) < 0) {