Re: [libvirt] [PATCH v2 4/8] util: Add safety net of checks to ensure valid object

The virObject logic "assumes" that whatever is passed to its API's would be some sort of virObjectPtr; however, if it is not then some really bad things can happen. So far there's been only virObject{Ref|Unref}, virObject{Lock|Unlock}, and virObjectIsClass and the virObject and virObjectLockable class consumers have been well behaved and code well tested. Soon there will be more consumers and one such consumer tripped over this during testing by passing a virHashTablePtr to virObjectIsClass which ends up calling virClassIsDerivedFrom using "obj->klass", which wasn't really a klass object causing one of those bad things to happen. To avoid the future possibility that a non virObject class memory was passed to some virObject* API, this patch adds two new checks - one to validate that the object has the 0xCAFExxxx value in obj->->u.s.magic and the other to ensure obj->u.s.magic doesn't "wrap" some day to 0xCAFF0000 if we ever get that many objects. It is still left up to the caller to handle the failed API calls just as it would be if it passed a NULL opaque pointer anyobj. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/util/virobject.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/src/util/virobject.c b/src/util/virobject.c index 9f5f187..e0465b1 100644 --- a/src/util/virobject.c +++ b/src/util/virobject.c

@@ -156,6 +159,7 @@ virClassNew(virClassPtr parent, if (VIR_STRDUP(klass->name, name) < 0) goto error; klass->magic = virAtomicIntInc(&magicCounter); + assert(klass->magic <= 0xCAFEFFFF);