From bf5a2fd38203f176501ad891da1e7ea19da1673a Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue, 25 Mar 2014 14:23:41 +0100
Subject: [PATCH 34/49] dmg: prevent out-of-bounds array access on terminator

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1395753835-7591-35-git-send-email-kwolf@redhat.com>
Patchwork-id: n/a
O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 34/48] dmg: prevent out-of-bounds array access on terminator
Bugzilla: 1066691
RH-Acked-by: Jeff Cody <jcody@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

From: Stefan Hajnoczi <stefanha@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1066691
Upstream status: Series embargoed

When a terminator is reached the base for offsets and sectors is stored.
The following records that are processed will use this base value.

If the first record we encounter is a terminator, then calculating the
base values would result in out-of-bounds array accesses. Don't do
that.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/dmg.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/block/dmg.c b/block/dmg.c
index be2f26e..f4f3e8e 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -182,7 +182,7 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
                 offset += 4;
                 if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
                     s->types[i] != 2) {
-                    if (s->types[i] == 0xffffffff) {
+                    if (s->types[i] == 0xffffffff && i > 0) {
                         last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
                         last_out_offset = s->sectors[i - 1] +
                                           s->sectorcounts[i - 1];
-- 
1.7.1