i2o: check copy_from_user() size parameter

Limit the size of the copy so we don't corrupt memory. Hopefully this
can only be called by root, but fixing this makes the static checkers
happier.

Signed-off-by: Dan Carpenter <[e-mail]>
Cc: Jiri Kosina <[e-mail]>
Cc: Masanari Iida <[e-mail]>
Cc: Alan Cox <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/message/i2o/i2o_config.c

···
 		}
 		size = size >> 16;
 		size *= 4;
+		if (size > sizeof(rmsg)) {
+			rcode = -EINVAL;
+			goto sg_list_cleanup;
+		}
+
 		/* Copy in the user's I2O command */
 		if (copy_from_user(rmsg, user_msg, size)) {
 			rcode = -EFAULT;
···
 		}
 		size = size >> 16;
 		size *= 4;
+		if (size > sizeof(rmsg)) {
+			rcode = -EFAULT;
+			goto sg_list_cleanup;
+		}
+
 		/* Copy in the user's I2O command */
 		if (copy_from_user(rmsg, user_msg, size)) {
 			rcode = -EFAULT;