spice/server/memslot.c
Christophe Fergeau a4a16ac42d memslot: Fix off-by-one error in group/slot boundary check
RedMemSlotInfo keeps an array of groups, and each group contains an
array of slots. Unfortunately, these checks are off by 1, they check
that the index is greater or equal to the number of elements in the
array, while these arrays are 0 based. The check should only check for
strictly greater than the number of elements.

For the group array, this is not a big issue, as these memslot groups
are created by spice-server users (eg QEMU), and the group ids used to
index that array are also generated by the spice-server user, so it
should not be possible for the guest to set them to arbitrary values.

The slot id is more problematic, as it's calculated from a QXLPHYSICAL
address, and such addresses are usually set by the guest QXL driver, so
the guest can set these to arbitrary values, including malicious values,
which are probably easy to build from the guest PCI configuration.

This patch fixes the arrays bound check, and adds a test case for this.
This fixes CVE-2019-3813.

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>
Acked-by: Frediano Ziglio <fziglio@redhat.com>
2019-02-05 14:05:49 +01:00

204 lines
6.5 KiB
C

/* -*- Mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
Copyright (C) 2009,2010 Red Hat, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <inttypes.h>
#include "memslot.h"
static unsigned long __get_clean_virt(RedMemSlotInfo *info, QXLPHYSICAL addr)
{
return addr & info->memslot_clean_virt_mask;
}
static void print_memslots(RedMemSlotInfo *info)
{
int i;
int x;
for (i = 0; i < info->num_memslots_groups; ++i) {
for (x = 0; x < info->num_memslots; ++x) {
if (!info->mem_slots[i][x].virt_start_addr &&
!info->mem_slots[i][x].virt_end_addr) {
continue;
}
printf("id %d, group %d, virt start %lx, virt end %lx, generation %u, delta %lx\n",
x, i, info->mem_slots[i][x].virt_start_addr,
info->mem_slots[i][x].virt_end_addr, info->mem_slots[i][x].generation,
info->mem_slots[i][x].address_delta);
}
}
}
/* return 1 if validation successfull, 0 otherwise */
int memslot_validate_virt(RedMemSlotInfo *info, unsigned long virt, int slot_id,
uint32_t add_size, uint32_t group_id)
{
MemSlot *slot;
slot = &info->mem_slots[group_id][slot_id];
if ((virt + add_size) < virt) {
spice_critical("virtual address overlap");
return 0;
}
if (virt < slot->virt_start_addr || (virt + add_size) > slot->virt_end_addr) {
print_memslots(info);
spice_warning("virtual address out of range"
" virt=0x%lx+0x%x slot_id=%d group_id=%d\n"
" slot=0x%lx-0x%lx delta=0x%lx",
virt, add_size, slot_id, group_id,
slot->virt_start_addr, slot->virt_end_addr, slot->address_delta);
return 0;
}
return 1;
}
unsigned long memslot_max_size_virt(RedMemSlotInfo *info,
unsigned long virt, int slot_id,
uint32_t group_id)
{
MemSlot *slot;
slot = &info->mem_slots[group_id][slot_id];
if (virt < slot->virt_start_addr || virt > slot->virt_end_addr) {
return 0;
}
return slot->virt_end_addr - virt;
}
/*
* returns NULL on failure.
*/
void *memslot_get_virt(RedMemSlotInfo *info, QXLPHYSICAL addr, uint32_t add_size,
int group_id)
{
int slot_id;
int generation;
unsigned long h_virt;
MemSlot *slot;
if (group_id >= info->num_memslots_groups) {
spice_critical("group_id too big");
return NULL;
}
slot_id = memslot_get_id(info, addr);
if (slot_id >= info->num_memslots) {
print_memslots(info);
spice_critical("slot_id %d too big, addr=%" PRIx64, slot_id, addr);
return NULL;
}
slot = &info->mem_slots[group_id][slot_id];
generation = memslot_get_generation(info, addr);
if (generation != slot->generation) {
print_memslots(info);
spice_critical("address generation is not valid, group_id %d, slot_id %d, "
"gen %d, slot_gen %d",
group_id, slot_id,
generation, slot->generation);
return NULL;
}
h_virt = __get_clean_virt(info, addr);
h_virt += slot->address_delta;
if (!memslot_validate_virt(info, h_virt, slot_id, add_size, group_id)) {
return NULL;
}
return (void*)(uintptr_t)h_virt;
}
void memslot_info_init(RedMemSlotInfo *info,
uint32_t num_groups, uint32_t num_slots,
uint8_t generation_bits,
uint8_t id_bits,
uint8_t internal_groupslot_id)
{
uint32_t i;
spice_assert(num_slots > 0);
spice_assert(num_groups > 0);
info->num_memslots_groups = num_groups;
info->num_memslots = num_slots;
info->generation_bits = generation_bits;
info->mem_slot_bits = id_bits;
info->internal_groupslot_id = internal_groupslot_id;
info->mem_slots = g_new(MemSlot *, num_groups);
for (i = 0; i < num_groups; ++i) {
info->mem_slots[i] = g_new0(MemSlot, num_slots);
}
/* TODO: use QXLPHYSICAL_BITS */
info->memslot_id_shift = 64 - info->mem_slot_bits;
info->memslot_gen_shift = 64 - (info->mem_slot_bits + info->generation_bits);
info->memslot_gen_mask = ~((QXLPHYSICAL)-1 << info->generation_bits);
info->memslot_clean_virt_mask = (((QXLPHYSICAL)(-1)) >>
(info->mem_slot_bits + info->generation_bits));
}
void memslot_info_destroy(RedMemSlotInfo *info)
{
uint32_t i;
for (i = 0; i < info->num_memslots_groups; ++i) {
g_free(info->mem_slots[i]);
}
g_free(info->mem_slots);
}
void memslot_info_add_slot(RedMemSlotInfo *info, uint32_t slot_group_id, uint32_t slot_id,
uint64_t addr_delta, unsigned long virt_start, unsigned long virt_end,
uint32_t generation)
{
spice_assert(info->num_memslots_groups > slot_group_id);
spice_assert(info->num_memslots > slot_id);
info->mem_slots[slot_group_id][slot_id].address_delta = addr_delta;
info->mem_slots[slot_group_id][slot_id].virt_start_addr = virt_start;
info->mem_slots[slot_group_id][slot_id].virt_end_addr = virt_end;
info->mem_slots[slot_group_id][slot_id].generation = generation;
}
void memslot_info_del_slot(RedMemSlotInfo *info, uint32_t slot_group_id, uint32_t slot_id)
{
spice_return_if_fail(info->num_memslots_groups > slot_group_id);
spice_return_if_fail(info->num_memslots > slot_id);
info->mem_slots[slot_group_id][slot_id].virt_start_addr = 0;
info->mem_slots[slot_group_id][slot_id].virt_end_addr = 0;
}
void memslot_info_reset(RedMemSlotInfo *info)
{
uint32_t i;
for (i = 0; i < info->num_memslots_groups; ++i) {
memset(info->mem_slots[i], 0, sizeof(MemSlot) * info->num_memslots);
}
}