Re: [PATCH] all arches, signal: Move restart_block to struct task_struct

[Al Viro]

On Sun, Oct 26, 2014 at 10:02:16AM -0700, Andy Lutomirski wrote:
> If an attacker can cause a controlled kernel stack overflow,
> overwriting the restart block is a very juicy exploit target.
> Moving the restart block to struct task_struct prevents this type of
> exploit.

The hell it does.  In a _lot_ of cases current is current_thread_info()->task,
which makes your variant just as vulnerable, in addition to being (slightly)
more costly.
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