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From b6b5b14e4190048fadbfbcf063d873d318127e81 Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <alan.coopersmith@oracle.com>
Date: Mon, 6 Jan 2014 23:30:14 -0800
Subject: [PATCH 20/40] dix: integer overflow in GetHosts() [CVE-2014-8092 2/4]
GetHosts() iterates over all the hosts it has in memory, and copies
them to a buffer. The buffer length is calculated by iterating over
all the hosts and adding up all of their combined length. There is a
potential integer overflow, if there are lots and lots of hosts (with
a combined length of > ~4 gig). This should be possible by repeatedly
calling ProcChangeHosts() on 64bit machines with enough memory.
This patch caps the list at 1mb, because multi-megabyte hostname
lists for X access control are insane.
v2: backport to nx-libs 3.6.x (Mike DePaulo)
v3: human-readable version of "1 MB" (Mihai Moldovan)
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Conflicts:
os/access.c
---
nx-X11/programs/Xserver/os/access.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/nx-X11/programs/Xserver/os/access.c
+++ b/nx-X11/programs/Xserver/os/access.c
@@ -1719,6 +1719,10 @@ GetHosts (
{
nHosts++;
n += (((host->len + 3) >> 2) << 2) + sizeof(xHostEntry);
+ /* Could check for INT_MAX, but in reality having more than 1mb of
+ hostnames in the access list is ridiculous */
+ if (n >= 1024*1024)
+ break;
}
if (n)
{
@@ -1730,6 +1734,8 @@ GetHosts (
for (host = validhosts; host; host = host->next)
{
len = host->len;
+ if ((ptr + sizeof(xHostEntry) + len) > (data + n))
+ break;
((xHostEntry *)ptr)->family = host->family;
((xHostEntry *)ptr)->length = len;
ptr += sizeof(xHostEntry);
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