[X2Go-Commits] [nx-libs] 06/06: dix: integer overflow in GetHosts() [CVE-2014-8092 2/4]

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x2go pushed a commit to branch 3.6.x
in repository nx-libs.

commit b6b5b14e4190048fadbfbcf063d873d318127e81
Author: Alan Coopersmith <alan.coopersmith at oracle.com>
Date:   Mon Jan 6 23:30:14 2014 -0800

    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 at ioactive.com>
    Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
    Reviewed-by: Peter Hutterer <peter.hutterer at who-t.net>
    
    Conflicts:
    	os/access.c
---
 nx-X11/programs/Xserver/os/access.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/nx-X11/programs/Xserver/os/access.c b/nx-X11/programs/Xserver/os/access.c
index b6a70a7..532a2f8 100644
--- 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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