Messages in this thread | | | Subject | Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen | From | Peter Zijlstra <> | Date | Sun, 10 May 2009 15:17:21 +0200 |
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On Sun, 2009-05-10 at 21:39 +0900, KOSAKI Motohiro wrote: > >> > They always use mmap(PROT_READ | PROT_WRITE | PROT_EXEC) for anycase. > >> > Please google it. you can find various example. > >> > >> How widely is PROT_EXEC abused? Would you share some of your google results? > > > > That's a security bug right there and should be fixed regardless of our > > heuristics. > > Yes, should be. but it's not security issue. it doesn't make any security hole. > Plus, this claim doesn't help to solve end-user problems.
Having more stuff executable than absolutely needed is always a security issue.
> I think the basic concept of the patch is right. > - executable mapping is important for good latency > - executable file is relatively small > > The last problem is, The patch assume executable mappings is rare, but > it isn't guranteed. > How do we separate truth executable mapping and mis-used PROT_EXEC usage?
One could possibly limit the size, but I don't think it pays to bother about this until we really run into it, again as Andrew already said, there's more ways to screw reclaim if you really want to.
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