[pve-devel] centos crash after livemigration fix

Derumier Alexandre aderumier at odiso.com
Fri Mar 2 09:17:44 CET 2012


Hi, I finnaly found a patch in the last patches serie from redhat developper.
(not yes apply in qemu or kvm tree,only in the mailing for the moment).

This correct a bug in usb initialize which cause kvm segfault on random guest os.







Check for dev->config being NULL in two places:
 USB_REQ_GET_CONFIGURATION and USB_REQ_GET_STATUS.

The behavior of USB_REQ_GET_STATUS is unspecified in the Default state,
that corresponds to dev->config being NULL (it defaults to NULL and is
reset whenever a SET_CONFIGURATION with value 0, or attachment). I
implemented it to correspond with the state before
ed5a83ddd8c1d8ec7b1015315530cf29949e7c48, the commit moving SET_STATUS
to usb-desc; if dev->config is not set we return whatever is in the
first configuration.

The behavior of USB_REQ_GET_CONFIGURATION is also undefined before any
SET_CONFIGURATION, but here we just return 0 (same as specified for the
Address state).

A win7 guest failed to initialize the device before this patch,
segfaulting when GET_STATUS was called with dev->config == NULL. With
this patch the passthrough device still doesn't work but the failure is
unrelated.



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