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From ae31d75c7c2872dfc2172921422bf6b1c8bb6b03 Mon Sep 17 00:00:00 2001
From: Bandan Das <bsd@redhat.com>
Date: Wed, 6 Nov 2013 02:11:01 +0100
Subject: [PATCH 54/81] kvmvapic: Catch invalid ROM size

RH-Author: Bandan Das <bsd@redhat.com>
Message-id: <1383703863-4840-1-git-send-email-bsd@redhat.com>
Patchwork-id: 55471
O-Subject: [PATCH RHEL-7.0 qemu-kvm 1/3] kvmvapic: Catch invalid ROM size
Bugzilla: 920021
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

From: Jan Kiszka <jan.kiszka@siemens.com>

If not caught early, a zero-length ROM will cause a NULL-pointer access
later on in patch_hypercalls when allocating a zero-length ROM copy and
trying to read from it.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 18e5eec4db96a00907eb588a2b803401637c7f67)

Conflicts:
	hw/i386/kvmvapic.c
---
 hw/i386/kvmvapic.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/i386/kvmvapic.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
index a7db94d..a2c7e8f 100644
--- a/hw/i386/kvmvapic.c
+++ b/hw/i386/kvmvapic.c
@@ -572,7 +572,7 @@ static int patch_hypercalls(VAPICROMState *s)
  * enable write access to the option ROM so that variables can be updated by
  * the guest.
  */
-static void vapic_map_rom_writable(VAPICROMState *s)
+static int vapic_map_rom_writable(VAPICROMState *s)
 {
     hwaddr rom_paddr = s->rom_state_paddr & ROM_BLOCK_MASK;
     MemoryRegionSection section;
@@ -593,6 +593,9 @@ static void vapic_map_rom_writable(VAPICROMState *s)
     /* read ROM size from RAM region */
     ram = memory_region_get_ram_ptr(section.mr);
     rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE;
+    if (rom_size == 0) {
+        return -1;
+    }
     s->rom_size = rom_size;
 
     /* We need to round to avoid creating subpages
@@ -605,11 +608,15 @@ static void vapic_map_rom_writable(VAPICROMState *s)
                              rom_size);
     memory_region_add_subregion_overlap(as, rom_paddr, &s->rom, 1000);
     s->rom_mapped_writable = true;
+
+    return 0;
 }
 
 static int vapic_prepare(VAPICROMState *s)
 {
-    vapic_map_rom_writable(s);
+    if (vapic_map_rom_writable(s) < 0) {
+        return -1;
+    }
 
     if (patch_hypercalls(s) < 0) {
         return -1;
-- 
1.7.1