Re: [PATCH] Fix crash when accessing block header of immediate values in pretty-printer

[Evan Hanson]

On 2020-10-21 18:17, megane wrote:
> Interesting.. How do you trigger this bug?

Here's a simple way:

    #;1> (pp (block-ref 'aardvark 0))
    
    Error: segmentation violation
    
            Call history:
    
            <syntax>          (pp (block-ref (quote aardvark) 0))
            <syntax>          (block-ref (quote aardvark) 0)
            <syntax>          (quote aardvark)
            <syntax>          (##core#quote aardvark)
            <eval>    (pp (block-ref (quote aardvark) 0))
            <eval>    (block-ref (quote aardvark) 0)        <--

I don't know how else #<unbound> can spring to life, but there might
be other ways? Of course one probably shouldn't do this, but we still
shouldn't segfault.

Evan