https://bugs.winehq.org/show_bug.cgi?id=46675
--- Comment #14 from tjb troyb@us.ibm.com --- (In reply to Zebediah Figura from comment #13)
Just from looking at the handle numbers in the log, I think the leak is coming from C:\Program Files\Steam\appcache, or one of the subsequent calls. The presence of FILE_FLAG_BACKUP_SEMANTICS nicely rules out any calls internal to Wine. I think we unfortunately have to assume that this is the program's fault. (Again, I don't think this is unbelievable on Windows: even if the program allocates 1.2 million handles, all of the memory for these can be paged to disk, and there's certainly more than 1.2 million handle numbers available.)
I ran in Win7 and it looks like you are right, it was up to 2000 handles in 20 minutes, same leak rate as under wine. I guess all I can do is to try to kludge in some kind of a timestamp based stale handle recovery queue into ntdll to run it on wine.