Re: [PATCH] Make LIST_POISON less deadly

[Avi Kivity]

Pavel Machek wrote:
> On Sun 2008-05-18 18:38:14, Avi Kivity 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 smaller than
> > the range spanned by pointer values.
> >     
>
> "Security hole unless arch maintainer does _foo_" sounds
> scary. Especially when i386 is hard to fix...
>   

It's a potential security hole.  You need to find a list corruption 
first.  The patch prevents escalation of the oops into a code injection.

i386 is fixable, though it will take more work than x86_64.

--
error compiling committee.c: too many arguments to function

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