Re: [PATCH] Make LIST_POISON less deadly (v3)

From: Ingo Molnar
Date: Tue May 20 2008 - 07:55:29 EST

* Avi Kivity <avi@xxxxxxxxxxxx> wrote:

> The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable
> pointers in order to trap erronous use of freed list_heads.
> Unfortunately userspace can arrange for those pointers to actually be
> dereferencable, potentially turning an oops to an expolit.
> To avoid this allow architectures (currently x86_64 only) to override
> the default values for these pointers with truly-undereferncable
> values. This is easy on x86_64 as the virtual address space is large
> and contains unmapped ranges.

looks good - thanks Avi - i've added your patch to the -tip tree. I have
opened a separate topic for it: tip/safe-poison-pointers. (because it
affects other architectures as well)

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