Re: [RFC/PATCH] revoke/frevoke system calls V2

From: Helge Hafting
Date: Fri Aug 11 2006 - 03:53:02 EST

Edgar Toernig wrote:
I wasn't aware of that (and I would definitely prefer a different behaviour).

But anyway, correct me if I'm wrong, revoke (V2) not simply removes the
pages from the mmaped area as truncating does (the vma stays); revoke
seems to completely remove the vma which is clearly a security bug.
Future mappings may silently get mapped into the area of the revoked
file without the app noticing it. It may then hand out data of the new
file still thinking it's sending the old one.
One could remap to /dev/null - the file would then be free to be
umounted, but the app could get confused. Or map inaccessible
pages, so the app segfault on the next access.

Helge Hafting
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