From 2cd62b5eb99ffbb2fce99f3c459455e630b35bf7 Mon Sep 17 00:00:00 2001 From: Alan Coopersmith Date: Fri, 1 Mar 2013 22:49:01 -0800 Subject: integer overflow in XListHosts() [CVE-2013-1981 5/13] If the reported number of host entries is too large, the calculations to allocate memory for them may overflow, leaving us writing beyond the bounds of the allocation. Reported-by: Ilja Van Sprundel Signed-off-by: Alan Coopersmith Reviewed-by: Matthieu Herrb --- src/LiHosts.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/src/LiHosts.c b/src/LiHosts.c index 0f5e837d..83cf3c79 100644 --- a/src/LiHosts.c +++ b/src/LiHosts.c @@ -62,6 +62,8 @@ X Window System is a trademark of The Open Group. #include #endif #include "Xlibint.h" +#include + /* * can be freed using XFree. */ @@ -73,7 +75,6 @@ XHostAddress *XListHosts ( { register XHostAddress *outbuf = NULL, *op; xListHostsReply reply; - long nbytes; unsigned char *buf, *bp; register unsigned i; register xListHostsReq *req; @@ -90,19 +91,26 @@ XHostAddress *XListHosts ( } if (reply.nHosts) { - nbytes = reply.length << 2; /* compute number of bytes in reply */ + unsigned long nbytes = reply.length << 2; /* number of bytes in reply */ + const unsigned long max_hosts = INT_MAX / + (sizeof(XHostAddress) + sizeof(XServerInterpretedAddress)); + + if (reply.nHosts < max_hosts) { + unsigned long hostbytes = reply.nHosts * + (sizeof(XHostAddress) + sizeof(XServerInterpretedAddress)); - op = outbuf = (XHostAddress *) - Xmalloc((unsigned) (nbytes + - (reply.nHosts * sizeof(XHostAddress)) + - (reply.nHosts * sizeof(XServerInterpretedAddress)))); + if (reply.length < (INT_MAX >> 2) && + (hostbytes >> 2) < ((INT_MAX >> 2) - reply.length)) + outbuf = Xmalloc(nbytes + hostbytes); + } if (! outbuf) { - _XEatData(dpy, (unsigned long) nbytes); + _XEatDataWords(dpy, reply.length); UnlockDisplay(dpy); SyncHandle(); return (XHostAddress *) NULL; } + op = outbuf; sip = (XServerInterpretedAddress *) (((unsigned char *) outbuf) + (reply.nHosts * sizeof(XHostAddress))); bp = buf = ((unsigned char *) sip) -- cgit v1.2.3