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From 014672abf617b4d0585640cdd56ce11cfb51800a Mon Sep 17 00:00:00 2001
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From: Alan Coopersmith <alan.coopersmith@oracle.com>
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Date: Mon, 6 Jan 2014 23:30:14 -0800
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Subject: [PATCH 03/33] dix: integer overflow in GetHosts() [CVE-2014-8092 2/4]
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GetHosts() iterates over all the hosts it has in memory, and copies
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them to a buffer. The buffer length is calculated by iterating over
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all the hosts and adding up all of their combined length. There is a
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potential integer overflow, if there are lots and lots of hosts (with
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a combined length of > ~4 gig). This should be possible by repeatedly
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calling ProcChangeHosts() on 64bit machines with enough memory.
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This patch caps the list at 1mb, because multi-megabyte hostname
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lists for X access control are insane.
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Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
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Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
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Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
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Signed-off-by: Fedora X Ninjas <x@fedoraproject.org>
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---
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os/access.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/os/access.c b/os/access.c
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index 6d991b3..dc12348 100644
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--- a/os/access.c
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+++ b/os/access.c
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@@ -1323,6 +1323,10 @@ GetHosts(pointer *data, int *pnHosts, int *pLen, BOOL * pEnabled)
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for (host = validhosts; host; host = host->next) {
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nHosts++;
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n += pad_to_int32(host->len) + sizeof(xHostEntry);
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+ /* Could check for INT_MAX, but in reality having more than 1mb of
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+ hostnames in the access list is ridiculous */
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+ if (n >= 1048576)
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+ break;
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}
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if (n) {
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*data = ptr = malloc(n);
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@@ -1331,6 +1335,8 @@ GetHosts(pointer *data, int *pnHosts, int *pLen, BOOL * pEnabled)
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}
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for (host = validhosts; host; host = host->next) {
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len = host->len;
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+ if ((ptr + sizeof(xHostEntry) + len) > (data + n))
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+ break;
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((xHostEntry *) ptr)->family = host->family;
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((xHostEntry *) ptr)->length = len;
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ptr += sizeof(xHostEntry);
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--
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1.9.3
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