[U-Boot] [PATCH] Handle environment variables like commands

[Wolfgang Denk]

Dear Petri Lehtinen,

In message <20081015104550.GB6881 at colossus> you wrote:
>
> > The command interpreter checks always if an environment variable
> > for that name exists and in this case the content of the variable
> > is executed. It becomes possible to redefine all U-Boot commands.
> > A new "builtin" command is added to be able to run builtin U-boot commands
> > even if they are redefined.
...
> It seems to me that the "builtin" command itself can still be
> redefined. Is this an issue?

Good catch. Yes, this must be prevented. Any variable named "builtin"
must be ignored here - i. e. we should issue  an  erro  when  someone
tries  a  "setenv", and ignore this variable explicitly (just in case
someone sneaks this into the default environment,  or  uses  un-fixed
Linux tools to create such a variable).

Thanks.

Best regards,

Wolfgang Denk

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