From 0604d191a2eba26cdda5ab6cb0f1917d6f379ba1 Mon Sep 17 00:00:00 2001
From: Gleb Natapov <gleb@redhat.com>
Date: Thu, 29 Jul 2010 14:11:52 -0300
Subject: [PATCH] Fix segfault in mmio subpage handling code.

RH-Author: Gleb Natapov <gleb@redhat.com>
Message-id: <patch-11083-clone-for-rhel55-rhel55>
Patchwork-id: 11091
O-Subject: [RHEL5.5/RHEL6 CVE-2010-2784 PATCH] Fix segfault in mmio subpage
	handling code.
Bugzilla: 619412
CVE: CVE-2010-2784
RH-Acked-by: Petr Matousek <pmatouse@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>

It is possible that subpage mmio is registered over existing memory
page. When this happens "memory" will have real memory address and not
index into io_mem array so next access to the page will generate
segfault. It is uncommon to have some part of a page to be accessed as
memory and some as mmio, but qemu shouldn't crash even when guest does
stupid things. So lets just pretend that the rest of the page is
unassigned if guest configure part of the memory page as mmio.

RHEL5.5. BZ: 619412
RHEL6 BZ: 619421

Upstream: similar patch was sent there.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
--
			Gleb.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/exec.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/qemu/exec.c b/qemu/exec.c
index becc8da..6943e56 100644
--- a/qemu/exec.c
+++ b/qemu/exec.c
@@ -2774,7 +2774,9 @@ static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
     printf("%s: %p start %08x end %08x idx %08x eidx %08x mem %d\n", __func__,
            mmio, start, end, idx, eidx, memory);
 #endif
-    memory >>= IO_MEM_SHIFT;
+    if ((memory & ~TARGET_PAGE_MASK) == IO_MEM_RAM)
+        memory = IO_MEM_UNASSIGNED;    
+    memory = (memory >> IO_MEM_SHIFT) & (IO_MEM_NB_ENTRIES - 1);
     for (; idx <= eidx; idx++) {
         for (i = 0; i < 4; i++) {
             if (io_mem_read[memory][i]) {
-- 
1.7.0.3