ISDN4Linux Bug in isdnhdlc.c

[Karsten Keil]

Hi,

Oskar found a critical bug in isdnhdlc.c, please
apply this simple fix to next versions.



From: Oskar Senft <oskar.senft@xxxxxx>

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@xxxxxxx>

diff -ur linux-2.6.11-rc2.org/drivers/isdn/hisax/isdnhdlc.c linux-2.6.11-rc2/drivers/isdn/hisax/isdnhdlc.c
--- linux-2.6.11-rc2.org/drivers/isdn/hisax/isdnhdlc.c	2004-11-23 15:53:25.000000000 +0100
+++ linux-2.6.11-rc2/drivers/isdn/hisax/isdnhdlc.c	2005-02-03 15:50:06.352137856 +0100
@@ -308,7 +308,7 @@
 				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

-- 
Karsten Keil
SuSE Labs
ISDN development
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