Re: [Qemu-devel] [PATCH for-2.1 for-stable] vmstate_xhci_event: fix unterminated field list

[Amit Shah <amit.shah@redhat.com>]

On (Tue) 22 Jul 2014 [17:26:41], Laszlo Ersek wrote:
> "vmstate_xhci_event" was introduced in commit 37352df3 ("xhci: add live
> migration support"), and first released in v1.6.0. The field list in this
> VMSD is not terminated with the VMSTATE_END_OF_LIST() macro.
> 
> During normal use (ie. migration), the issue is practically invisible,
> because the "vmstate_xhci_event" object (with the unterminated field list)
> is only ever referenced -- via "vmstate_xhci_intr" -- if xhci_er_full()
> returns true, for the "ev_buffer" test. Since that field_exists() check
> (apparently) almost always returns false, we almost never traverse
> "vmstate_xhci_event" during migration, which hides the bug.
> 
> However, Amit's vmstate checker forces recursion into this VMSD as well,
> and the lack of VMSTATE_END_OF_LIST() breaks the field list terminator
> check (field->name != NULL) in dump_vmstate_vmsd(). The result is
> undefined behavior, which in my case translates to infinite recursion
> (because the loop happens to overflow into "vmstate_xhci_intr", which then
> links back to "vmstate_xhci_event").
> 
> Add the missing terminator.
> 
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>

Thanks for spotting this!

Reviewed-by: Amit Shah <amit.shah@redhat.com>


		Amit