[PATCH] ISDN: check for userspace copy faults

Most of the ISDN ->readstat() implementations needed to check
copy_to_user() and put_user() return values.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c
index 23afba4..c3ae2ed 100644
--- a/drivers/isdn/isdnloop/isdnloop.c
+++ b/drivers/isdn/isdnloop/isdnloop.c
@@ -446,7 +446,8 @@
 	for (p = buf, count = 0; count < len; p++, count++) {
 		if (card->msg_buf_read == card->msg_buf_write)
 			return count;
-		put_user(*card->msg_buf_read++, p);
+		if (put_user(*card->msg_buf_read++, p))
+			return -EFAULT;
 		if (card->msg_buf_read > card->msg_buf_end)
 			card->msg_buf_read = card->msg_buf;
 	}