| Message ID | 1295861427-30851-1-git-send-email-tamura.yoshiaki@lab.ntt.co.jp |
|---|---|
| State | New |
| Headers | show |
On 01/24/2011 10:30 AM, Yoshiaki Tamura 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. > > Signed-off-by: Yoshiaki Tamura<tamura.yoshiaki@lab.ntt.co.jp> VMS_STRUCT is a can of worms, since almost all uses of subsections _are_ VMS_STRUCTs. So almost all uses of subsections have ambiguous parsing. :/ So, for now, Acked-by: Paolo Bonzini <pbonzini@redhat.com> Paolo
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.yoshiaki@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
On 06/09/2011 02:48 PM, Kevin Wolf wrote: > 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? Unfortunately you cannot have it both ways because the migration format is ambiguous. > 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. I would have expected migration to fail anyway because the next instances are not parsed correctly. Paolo
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; + } + while (qemu_peek_byte(f) == QEMU_VM_SUBSECTION) { char idstr[256]; int ret; @@ -1651,10 +1657,11 @@ 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; @@ -1678,6 +1685,7 @@ 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++;
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.yoshiaki@lab.ntt.co.jp> --- savevm.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-)