Fix CVE-2017-11334:

https://bugzilla.redhat.com/show_bug.cgi?id=1471638
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-11334

Patch copied from upstream source repository:

http://git.qemu.org/?p=qemu.git;a=commitdiff;h=04bf2526ce87f21b32c9acba1c5518708c243ad0

From 04bf2526ce87f21b32c9acba1c5518708c243ad0 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Wed, 12 Jul 2017 18:08:40 +0530
Subject: [PATCH] exec: use qemu_ram_ptr_length to access guest ram

When accessing guest's ram block during DMA operation, use
'qemu_ram_ptr_length' to get ram block pointer. It ensures
that DMA operation of given length is possible; And avoids
any OOB memory access situations.

Reported-by: Alex <broscutamaker@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-Id: <20170712123840.29328-1-ppandit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 exec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/exec.c b/exec.c
index a083ff89ad..ad103ce483 100644
--- a/exec.c
+++ b/exec.c
@@ -2929,7 +2929,7 @@ static MemTxResult address_space_write_continue(AddressSpace *as, hwaddr addr,
             }
         } else {
             /* RAM case */
-            ptr = qemu_map_ram_ptr(mr->ram_block, addr1);
+            ptr = qemu_ram_ptr_length(mr->ram_block, addr1, &l);
             memcpy(ptr, buf, l);
             invalidate_and_set_dirty(mr, addr1, l);
         }
@@ -3020,7 +3020,7 @@ MemTxResult address_space_read_continue(AddressSpace *as, hwaddr addr,
             }
         } else {
             /* RAM case */
-            ptr = qemu_map_ram_ptr(mr->ram_block, addr1);
+            ptr = qemu_ram_ptr_length(mr->ram_block, addr1, &l);
             memcpy(buf, ptr, l);
         }
 
-- 
2.13.3

