From bc8e20430b6f6378daf6ce4329029248a88af08b 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] 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.
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>
---
os/access.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/os/access.c b/os/access.c
index 5c510ded2e..f393c8d54c 100644
--- a/os/access.c
+++ b/os/access.c
@@ -1296,6 +1296,10 @@ GetHosts(void **data, int *pnHosts, int *pLen, BOOL * pEnabled)
for (host = validhosts; host; host = host->next) {
nHosts++;
n += pad_to_int32(host->len) + sizeof(xHostEntry);
+ /* Could check for INT_MAX, but in reality having more than 1mb of
+ hostnames in the access list is ridiculous */
+ if (n >= 1048576)
+ break;
}
if (n) {
*data = ptr = malloc(n);
@@ -1304,6 +1308,8 @@ GetHosts(void **data, int *pnHosts, int *pLen, BOOL * pEnabled)
}
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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