From 144849ea27230962227e62a943b399e2ab304787 Mon Sep 17 00:00:00 2001 From: Matthieu Herrb Date: Tue, 18 Aug 2020 14:52:29 +0200 Subject: [PATCH] Fix XkbSelectEvents() integer underflow CVE-2020-14361 ZDI-CAN 11573 This vulnerability was discovered by: Jan-Niklas Sohn working with Trend Micro Zero Day Initiative Signed-off-by: Matthieu Herrb --- xkb/xkbSwap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xkb/xkbSwap.c b/xkb/xkbSwap.c index 1c1ed5ff4..50cabb90e 100644 --- a/xkb/xkbSwap.c +++ b/xkb/xkbSwap.c @@ -76,7 +76,7 @@ SProcXkbSelectEvents(ClientPtr client) register unsigned bit, ndx, maskLeft, dataLeft, size; from.c8 = (CARD8 *) &stuff[1]; - dataLeft = (stuff->length * 4) - SIZEOF(xkbSelectEventsReq); + dataLeft = (client->req_len * 4) - SIZEOF(xkbSelectEventsReq); maskLeft = (stuff->affectWhich & (~XkbMapNotifyMask)); for (ndx = 0, bit = 1; (maskLeft != 0); ndx++, bit <<= 1) { if (((bit & maskLeft) == 0) || (ndx == XkbMapNotify))