[OpenBIOS] [PATCH 2/2] Don't map the page 0 to make NULL-dereferencing more obvious

Tarl Neustaedter tarl-b2 at tarl.net
Wed Apr 10 17:47:20 CEST 2013

On 2013-Apr-10 04:18 , Mark Cave-Ayland wrote:
> [...]
> Hmmm the source looks like this:
> " /chosen" find-dev if
>   " mmu" rot get-package-property 0= if
>     decode-int nip nip ihandle>phandle active-package = if
>     ...
>     then
>   then
> then
> AFAICT the code should get the chosen package "mmu" property, decode 
> it, remove the remainder, convert to a phandle and then do the 
> comparison to active-package which should be valid?

Ah. Sorry, I was mistaken in what was going on in .properties. I thought 
it was doing an ihandle>phandle on the returned value of active-package. 
Looking more carefully at the stack trace, it's indeed doing an 
ihandle>phandle on the result of a get-package-property rather than 
active-package - the " mmu" property is coming back zero, and you really 
can't feed that to ihandle>phandle.

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