hurd: Make __if_nametoindex return ENODEV if ifname is too long

rather than truncating it.

	* sysdeps/mach/hurd/if_index.c (__if_nametoindex): Return ENODEV if
	ifname is too long.

2 files changed, 8 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index dd78bf6..cc96132 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -35,8 +35,8 @@
 
 2018-04-03  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
-	* sysdeps/mach/hurd/if_index.c (__if_nametoindex): Always end
-	ifr.fr_name with a NUL caracter.
+	* sysdeps/mach/hurd/if_index.c (__if_nametoindex): Return ENODEV if
+	ifname is too long.
 
 2018-04-03  Wilco Dijkstra  <wdijkstr@arm.com>
 
diff --git a/sysdeps/mach/hurd/if_index.c b/sysdeps/mach/hurd/if_index.c
index 7f647b7..b56bfc7 100644
--- a/sysdeps/mach/hurd/if_index.c
+++ b/sysdeps/mach/hurd/if_index.c
@@ -37,9 +37,13 @@ __if_nametoindex (const char *ifname)
   if (fd < 0)
     return 0;
 
-  strncpy (ifr.ifr_name, ifname, IFNAMSIZ - 1);
-  ifr.ifr_name[IFNAMESIZ - 1] = '\0';
+  if (strlen (ifname) >= IFNAMSIZ)
+    {
+      __set_errno (ENODEV);
+      return 0;
+    }
 
+  strncpy (ifr.ifr_name, ifname, IFNAMESIZ - 1);
   if (__ioctl (fd, SIOCGIFINDEX, &ifr) < 0)
     {
       int saved_errno = errno;