[PATCH] Fix ISDN4Linux bug in isdnhdlc.c

isdnhdlc_decode is called multiple times for bigger frames, so
decrementing dsize is a bad idea and can cause a overflow of
the dst buffer.
Signed-off-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/isdn/hisax/isdnhdlc.c

@@ -308,7 +308,7 @@ int isdnhdlc_decode (struct isdnhdlc_vars *hdlc, const unsigned char *src,
 				hdlc->crc = crc_ccitt_byte(hdlc->crc, hdlc->shift_reg);
 
 				// good byte received
-				if (dsize--) {
+				if (hdlc->dstpos < dsize) {
 					dst[hdlc->dstpos++] = hdlc->shift_reg;
 				} else {
 					// frame too long