qemu/hw/nvram/mac_nvram.c
Greg Kurz 37035df51e nvram: Exit QEMU if NVRAM cannot contain all -prom-env data
Since commit 61f20b9dc5 ("spapr_nvram: Pre-initialize the NVRAM to
support the -prom-env parameter"), pseries machines can pre-initialize
the "system" partition in the NVRAM with the data passed to all -prom-env
parameters on the QEMU command line.

In this case it is assumed that all the data fits in 64 KiB, but the user
can easily pass more and crash QEMU:

$ qemu-system-ppc64 -M pseries $(for ((x=0;x<128;x++)); do \
  echo -n " -prom-env " ; printf "%0.sx" {1..1024}; \
  done) # this requires ~128 Kib
malloc(): corrupted top size
Aborted (core dumped)

This happens because we don't check if all the prom-env data fits in
the NVRAM and chrp_nvram_set_var() happily memcpy() it passed the
buffer.

This crash affects basically all ppc/ppc64 machine types that use -prom-env:
- pseries (all versions)
- g3beige
- mac99

and also sparc/sparc64 machine types:
- LX
- SPARCClassic
- SPARCbook
- SS-10
- SS-20
- SS-4
- SS-5
- SS-600MP
- Voyager
- sun4u
- sun4v

Add a max_len argument to chrp_nvram_create_system_partition() so that
it can check the available size before writing to memory.

Since NVRAM is populated at machine init, it seems reasonable to consider
this error as fatal. So, instead of reporting an error when we detect that
the NVRAM is too small and adapt all machine types to handle it, we simply
exit QEMU in all cases. This is still better than crashing. If someone
wants another behavior, I guess this can be reworked later.

Tested with:

$ yes q | \
  (for arch in ppc ppc64 sparc sparc64; do \
       echo == $arch ==; \
       qemu=${arch}-softmmu/qemu-system-$arch; \
       for mach in $($qemu -M help | awk '! /^Supported/ { print $1 }'); do \
           echo $mach; \
           $qemu -M $mach -monitor stdio -nodefaults -nographic \
           $(for ((x=0;x<128;x++)); do \
                 echo -n " -prom-env " ; printf "%0.sx" {1..1024}; \
             done) >/dev/null; \
        done; echo; \
   done)

Without the patch, affected machine types cause QEMU to report some
memory corruption and crash:

malloc(): corrupted top size

free(): invalid size

*** stack smashing detected ***: terminated

With the patch, QEMU prints the following message and exits:

NVRAM is too small. Try to pass less data to -prom-env

It seems that the conditions for the crash have always existed, but it
affects pseries, the machine type I care for, since commit 61f20b9dc5
only.

Fixes: 61f20b9dc5 ("spapr_nvram: Pre-initialize the NVRAM to support the -prom-env parameter")
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1867739
Reported-by: John Snow <jsnow@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <159736033937.350502.12402444542194031035.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2020-08-14 13:34:31 +10:00

186 lines
5.6 KiB
C

/*
* PowerMac NVRAM emulation
*
* Copyright (c) 2005-2007 Fabrice Bellard
* Copyright (c) 2007 Jocelyn Mayer
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "hw/nvram/chrp_nvram.h"
#include "hw/ppc/mac.h"
#include "hw/qdev-properties.h"
#include "migration/vmstate.h"
#include "qemu/cutils.h"
#include "qemu/module.h"
#include "trace.h"
#include <zlib.h>
#define DEF_SYSTEM_SIZE 0xc10
/* macio style NVRAM device */
static void macio_nvram_writeb(void *opaque, hwaddr addr,
uint64_t value, unsigned size)
{
MacIONVRAMState *s = opaque;
addr = (addr >> s->it_shift) & (s->size - 1);
trace_macio_nvram_write(addr, value);
s->data[addr] = value;
}
static uint64_t macio_nvram_readb(void *opaque, hwaddr addr,
unsigned size)
{
MacIONVRAMState *s = opaque;
uint32_t value;
addr = (addr >> s->it_shift) & (s->size - 1);
value = s->data[addr];
trace_macio_nvram_read(addr, value);
return value;
}
static const MemoryRegionOps macio_nvram_ops = {
.read = macio_nvram_readb,
.write = macio_nvram_writeb,
.valid.min_access_size = 1,
.valid.max_access_size = 4,
.impl.min_access_size = 1,
.impl.max_access_size = 1,
.endianness = DEVICE_BIG_ENDIAN,
};
static const VMStateDescription vmstate_macio_nvram = {
.name = "macio_nvram",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VBUFFER_UINT32(data, MacIONVRAMState, 0, NULL, size),
VMSTATE_END_OF_LIST()
}
};
static void macio_nvram_reset(DeviceState *dev)
{
}
static void macio_nvram_realizefn(DeviceState *dev, Error **errp)
{
SysBusDevice *d = SYS_BUS_DEVICE(dev);
MacIONVRAMState *s = MACIO_NVRAM(dev);
s->data = g_malloc0(s->size);
memory_region_init_io(&s->mem, OBJECT(s), &macio_nvram_ops, s,
"macio-nvram", s->size << s->it_shift);
sysbus_init_mmio(d, &s->mem);
}
static void macio_nvram_unrealizefn(DeviceState *dev)
{
MacIONVRAMState *s = MACIO_NVRAM(dev);
g_free(s->data);
}
static Property macio_nvram_properties[] = {
DEFINE_PROP_UINT32("size", MacIONVRAMState, size, 0),
DEFINE_PROP_UINT32("it_shift", MacIONVRAMState, it_shift, 0),
DEFINE_PROP_END_OF_LIST()
};
static void macio_nvram_class_init(ObjectClass *oc, void *data)
{
DeviceClass *dc = DEVICE_CLASS(oc);
dc->realize = macio_nvram_realizefn;
dc->unrealize = macio_nvram_unrealizefn;
dc->reset = macio_nvram_reset;
dc->vmsd = &vmstate_macio_nvram;
device_class_set_props(dc, macio_nvram_properties);
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
}
static const TypeInfo macio_nvram_type_info = {
.name = TYPE_MACIO_NVRAM,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(MacIONVRAMState),
.class_init = macio_nvram_class_init,
};
static void macio_nvram_register_types(void)
{
type_register_static(&macio_nvram_type_info);
}
/* Set up a system OpenBIOS NVRAM partition */
static void pmac_format_nvram_partition_of(MacIONVRAMState *nvr, int off,
int len)
{
int sysp_end;
/* OpenBIOS nvram variables partition */
sysp_end = chrp_nvram_create_system_partition(&nvr->data[off],
DEF_SYSTEM_SIZE, len) + off;
/* Free space partition */
chrp_nvram_create_free_partition(&nvr->data[sysp_end], len - sysp_end);
}
#define OSX_NVRAM_SIGNATURE (0x5A)
/* Set up a Mac OS X NVRAM partition */
static void pmac_format_nvram_partition_osx(MacIONVRAMState *nvr, int off,
int len)
{
uint32_t start = off;
ChrpNvramPartHdr *part_header;
unsigned char *data = &nvr->data[start];
/* empty partition */
part_header = (ChrpNvramPartHdr *)data;
part_header->signature = OSX_NVRAM_SIGNATURE;
pstrcpy(part_header->name, sizeof(part_header->name), "wwwwwwwwwwww");
chrp_nvram_finish_partition(part_header, len);
/* Generation */
stl_be_p(&data[20], 2);
/* Adler32 checksum */
stl_be_p(&data[16], adler32(0, &data[20], len - 20));
}
/* Set up NVRAM with OF and OSX partitions */
void pmac_format_nvram_partition(MacIONVRAMState *nvr, int len)
{
/*
* Mac OS X expects side "B" of the flash at the second half of NVRAM,
* so we use half of the chip for OF and the other half for a free OSX
* partition.
*/
pmac_format_nvram_partition_of(nvr, 0, len / 2);
pmac_format_nvram_partition_osx(nvr, len / 2, len / 2);
}
type_init(macio_nvram_register_types)