Yoshiaki Tamura <tamura.yoshi...@lab.ntt.co.jp> wrote:
> Although it's rare to happen in live migration, when the head of a
> byte stream contains 0x05 which is the marker of subsection, the
> loader gets corrupted because vmstate_subsection_load() continues even
> the device doesn't require it. This patch adds a checker whether
> subsection is needed, and skips following routines if not needed.
This only fixes "partially" the problem :(
I agree with bonzini that it is better than what we had until we get the
time to try a better aproach. I was thinking about only allowing
subsections at the top level, but that still don't improve things, would
have to think more about the problem.
Reviewed-by: Juan Quintela <quint...@redhat.com>
> Signed-off-by: Yoshiaki Tamura <tamura.yoshi...@lab.ntt.co.jp>
> Acked-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> savevm.c | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index 4453217..6d83b0f 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -1638,6 +1638,12 @@ static const VMStateDescription
> *vmstate_get_subsection(const VMStateSubsection
> static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription
> *vmsd,
> void *opaque)
> {
> + const VMStateSubsection *sub = vmsd->subsections;
> +
> + if (!sub || !sub->needed) {
> + return 0;
> + }
> +
> while (qemu_peek_byte(f) == QEMU_VM_SUBSECTION) {
> char idstr[256];
> int ret;
> @@ -1650,10 +1656,11 @@ static int vmstate_subsection_load(QEMUFile *f, const
> VMStateDescription *vmsd,
> idstr[len] = 0;
> version_id = qemu_get_be32(f);
>
> - sub_vmsd = vmstate_get_subsection(vmsd->subsections, idstr);
> + sub_vmsd = vmstate_get_subsection(sub, idstr);
> if (sub_vmsd == NULL) {
> return -ENOENT;
> }
> + assert(!sub_vmsd->subsections);
> ret = vmstate_load_state(f, sub_vmsd, opaque, version_id);
> if (ret) {
> return ret;
> @@ -1677,6 +1684,7 @@ static void vmstate_subsection_save(QEMUFile *f, const
> VMStateDescription *vmsd,
> qemu_put_byte(f, len);
> qemu_put_buffer(f, (uint8_t *)vmsd->name, len);
> qemu_put_be32(f, vmsd->version_id);
> + assert(!vmsd->subsections);
> vmstate_save_state(f, vmsd, opaque);
> }
> sub++;
