console: Fix console name size mismatch

commit 30a22c21 upstream.

commit 6ae9200f ("enlarge console.name") increased the storage
for the console name to 16 bytes, but not the corresponding
struct console_cmdline::name storage. Console names longer than
8 bytes cause read beyond end-of-string and failure to match
console; I'm not sure if there are other unexpected consequences.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/printk.c

@@ -107,7 +107,7 @@ static struct console *exclusive_console;
  */
 struct console_cmdline
 {
-	char	name[8];			/* Name of the driver	    */
+	char	name[16];			/* Name of the driver	    */
 	int	index;				/* Minor dev. to use	    */
 	char	*options;			/* Options for the driver   */
 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
@@ -2290,6 +2290,8 @@ void register_console(struct console *newcon)
 	 */
 	for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
 			i++) {
+		BUILD_BUG_ON(sizeof(console_cmdline[i].name) !=
+			     sizeof(newcon->name));
 		if (strcmp(console_cmdline[i].name, newcon->name) != 0)
 			continue;
 		if (newcon->index >= 0 &&