[PATCH 5/8] server: Notify client about freed object so that it may free associated kernel object.

[Jacek Caban]

Hi Derek,

On 3/15/19 6:15 PM, Derek Lesho wrote:
> I am also curious about something, what was wrong w/ the old
> infrastructure where the object structure held the list to
> kernel_objects?


It's mostly about safety. Note that server does not trust clients to be 
sane, even if the client is a kernel in Windows sense. The patchset 
allowed storing a reference to an arbitrary handle-accessible object. 
Although from object's perspective it mostly behaves like yet another 
handle, it's not exactly the same (otherwise it wouldn't make sense to 
introduce it). There are some corner cases where kernel process could 
harm wineserver if it's not treated with care. For example it could try 
store a reference to device manager (something Windows application would 
not do since there is no such thing as server device manager handle on 
Windows), which would cause circular dependency and a leak. In previous 
patchset I tried to catch such cases. Avoiding the above needed a 
special case, which wasn't really nice. Allowing references on only 
explicitly whitelisted object types solves the problem.


Jacek