On Wednesday, April 17, 2024 3:02:13 PM CDT Elizabeth Figura wrote:
Except for the "unowned" semantics of zero, the actual value of the owner identifier is not interpreted by the ntsync driver at all. The intended use is to store a thread identifier; however, the ntsync driver does not actually validate that a calling thread provides consistent or unique identifiers.
Why not verify it? Seems simple enough to put in a TID check, esp. if NT mandates the same.
I mostly figured it'd be simplest to leave the driver completely agnostic, but I don't think there's any reason we can't use the real TID for most calls.
While trying to implement this I did realize a reason: if a Linux thread dies and a new Wine thread is created which happens to have the same Linux TID *before* Wine notices the thread death, that thread's TID will be conflated with the thread that died. I don't think we can guarantee that we notice thread death before we notice a request to create a new Wine thread.
Using Wine-managed TIDs avoids this by virtue of ensuring that a Wine TID is not reused until the associated Wine thread has been cleaned up.