Am 24.01.2011 10:30, schrieb Yoshiaki Tamura:
> 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.
>
> Signed-off-by: Yoshiaki Tamura <tamura.yoshi...@lab.ntt.co.jp>
> ---
> savevm.c | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index fcd8db4..3be875d 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -1639,6 +1639,12 @@ 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;
> + }
This means that subsections are silently ignored if the old version
didn't have any subsection for the device. Wasn't it a fundamental point
of the design of subsections that this would fail?
Noticed this when trying to use subsections to fix up IDE, and new ->
old migration after an I/O error only correctly fails when I revert this
patch.
Kevin
