Re: Shared system resources

HI George,

Thanks, this information clears the situation. Now, question to you and
David.

May we run into situation, when attacker dumps memory and analyses it for
valuable content, instead of reserving it for own process, where it would
be zeroed? My understanding, it is a possibility. Does kernel have any
safeguard against it?

Thanks,

Oleg

On Wed, Dec 23, 2015 at 2:13 AM, George Neuner <gneuner2(at)comcast(dot)net> wrote:

> On Tue, 22 Dec 2015 23:21:27 +0000, David Wilson <dw+pg(at)hmmz(dot)org>
> wrote:
>
> >On Linux the memory pages of an exiting process aren't sanitized at
> >exit, however it is impossible(?) for userspace to reallocate them
> >without the kernel first zeroing their contents.
>
> Not impossible, but it requires a non-standard kernel.
>
> Since 2.6.33, mmap() accepts the flag MAP_UNINITIALIZED which allows
> pages to be mapped without being cleared. The flag has no effect
> unless the kernel was built with CONFIG_MMAP_ALLOW_UNINITIALIZED.
>
>
> No mainstream distro enables this. AFAIK, there is NO distro at all
> that enables it ... it's too big a security risk for a general purpose
> system. It's intended to support embedded systems where the set of
> programs is known.
>
> George
>
>
>
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