autofs4: fix string validation check order

In function validate_dev_ioctl() we check that the string we've been sent
is a valid path. The function that does this check assumes the string is
NULL terminated but our NULL termination check isn't done until after this
call. This patch changes the order of the check.

Signed-off-by: Ian Kent <[e-mail]>
Acked-by: Jeff Moyer <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/autofs4/dev-ioctl.c

···
 
 /*
  * Check sanity of parameter control fields and if a path is present
- * check that it has a "/" and is terminated.
+ * check that it is terminated and contains at least one "/".
  */
 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 {
···
 	}
 
 	if (param->size > sizeof(*param)) {
-		err = check_name(param->path);
+		err = invalid_str(param->path,
+				 (void *) ((size_t) param + param->size));
 		if (err) {
-			AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
-				    cmd);
+			AUTOFS_WARN(
+			  "path string terminator missing for cmd(0x%08x)",
+			  cmd);
 			goto out;
 		}
 
-		err = invalid_str(param->path,
-				 (void *) ((size_t) param + param->size));
+		err = check_name(param->path);
 		if (err) {
 			AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 				    cmd);