hwmon: (applesmc) Limit key length in warning messages

Key lookups may call read_smc() with a fixed-length key string,
and if the lookup fails, trailing stack content may appear in the
kernel log. Fixed with this patch.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/applesmc.c

@@ -215,15 +215,15 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
 	int i;
 
 	if (send_command(cmd) || send_argument(key)) {
-		pr_warn("%s: read arg fail\n", key);
+		pr_warn("%.4s: read arg fail\n", key);
 		return -EIO;
 	}
 
 	outb(len, APPLESMC_DATA_PORT);
 
 	for (i = 0; i < len; i++) {
 		if (__wait_status(0x05)) {
-			pr_warn("%s: read data fail\n", key);
+			pr_warn("%.4s: read data fail\n", key);
 			return -EIO;
 		}
 		buffer[i] = inb(APPLESMC_DATA_PORT);