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From ae31d75c7c2872dfc2172921422bf6b1c8bb6b03 Mon Sep 17 00:00:00 2001
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From: Bandan Das <bsd@redhat.com>
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Date: Wed, 6 Nov 2013 02:11:01 +0100
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Subject: [PATCH 54/81] kvmvapic: Catch invalid ROM size
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RH-Author: Bandan Das <bsd@redhat.com>
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Message-id: <1383703863-4840-1-git-send-email-bsd@redhat.com>
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Patchwork-id: 55471
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O-Subject: [PATCH RHEL-7.0 qemu-kvm 1/3] kvmvapic: Catch invalid ROM size
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Bugzilla: 920021
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
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RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>
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From: Jan Kiszka <jan.kiszka@siemens.com>
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If not caught early, a zero-length ROM will cause a NULL-pointer access
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later on in patch_hypercalls when allocating a zero-length ROM copy and
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trying to read from it.
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Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 18e5eec4db96a00907eb588a2b803401637c7f67)
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Conflicts:
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	hw/i386/kvmvapic.c
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---
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 hw/i386/kvmvapic.c | 11 +++++++++--
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 1 file changed, 9 insertions(+), 2 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/i386/kvmvapic.c |   11 +++++++++--
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 1 files changed, 9 insertions(+), 2 deletions(-)
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diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
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index a7db94d..a2c7e8f 100644
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--- a/hw/i386/kvmvapic.c
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+++ b/hw/i386/kvmvapic.c
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@@ -572,7 +572,7 @@ static int patch_hypercalls(VAPICROMState *s)
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  * enable write access to the option ROM so that variables can be updated by
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  * the guest.
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  */
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-static void vapic_map_rom_writable(VAPICROMState *s)
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+static int vapic_map_rom_writable(VAPICROMState *s)
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 {
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     hwaddr rom_paddr = s->rom_state_paddr & ROM_BLOCK_MASK;
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     MemoryRegionSection section;
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@@ -593,6 +593,9 @@ static void vapic_map_rom_writable(VAPICROMState *s)
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     /* read ROM size from RAM region */
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     ram = memory_region_get_ram_ptr(section.mr);
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     rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE;
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+    if (rom_size == 0) {
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+        return -1;
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+    }
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     s->rom_size = rom_size;
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     /* We need to round to avoid creating subpages
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@@ -605,11 +608,15 @@ static void vapic_map_rom_writable(VAPICROMState *s)
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                              rom_size);
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     memory_region_add_subregion_overlap(as, rom_paddr, &s->rom, 1000);
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     s->rom_mapped_writable = true;
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+
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+    return 0;
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 }
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 static int vapic_prepare(VAPICROMState *s)
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 {
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-    vapic_map_rom_writable(s);
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+    if (vapic_map_rom_writable(s) < 0) {
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+        return -1;
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+    }
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     if (patch_hypercalls(s) < 0) {
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         return -1;
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-- 
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1.7.1
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