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SubjectRe: [RFC][PATCH v2] procfs: Always expose /proc/<pid>/map_files/ and make it readable
On Mon, Jan 26, 2015 at 10:50:23PM -0800, Andrew Morton wrote:
> On Tue, 27 Jan 2015 09:46:47 +0300 Cyrill Gorcunov <> wrote:
> > > There's one other problem here: we're assuming that the map_files
> > > implementation doesn't have bugs. If it does have bugs then relaxing
> > > permissions like this will create new vulnerabilities. And the
> > > map_files implementation is surprisingly complex. Is it bug-free?
> >
> > I didn't find any bugs in map-files (and we use it for long time already)
> > so I think it is safe.
> You've been using map_files the way it was supposed to be used so no,
> any bugs won't show up. What happens if you don your evil black hat
> and use map_files in ways that weren't anticipated? Attack it?

Hard to say, Andrew. If I found a way to exploit this feature for
bad purpose for sure I would patch it out. At the moment I don't
see any. Touching another process memory via file descriptor
allows one to modify its contents but you have to be granted
ptrace-may-access which i consider as enough for security.

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