Re: [Minios-devel] [UNIKRAFT PATCH] lib/alloc: check for missing palloc implementation

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hi Hugo,

thanks a lot for your work. This is a good finding.

On 08.01.20 11:26, Hugo Lefeuvre wrote:
> Add NULL pointer check to uk_palloc in order to avoid NULL pointer
> dereference when palloc is not implemented by the allocator.
> ---
>   lib/ukalloc/include/uk/alloc.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/ukalloc/include/uk/alloc.h b/lib/ukalloc/include/uk/alloc.h
> index 634bb3f..2e73ab6 100644
> --- a/lib/ukalloc/include/uk/alloc.h
> +++ b/lib/ukalloc/include/uk/alloc.h
> @@ -201,7 +201,7 @@ static inline void *uk_do_palloc(struct uk_alloc *a, size_t 
> order)
>   }
>   static inline void *uk_palloc(struct uk_alloc *a, size_t order)
>   {
> -       if (unlikely(!a))
> +       if (unlikely(!a) || unlikely(!a->palloc))
Interesting... I am actually curious what the compiler does with your 
condition. I would have written it with just one encapsulating 
`unlikely` hint:
if (unlikely(!a || !a->palloc))

Maybe there is no difference and it turns out to be different coding 
style. In general, having just one encapsulating hint maybe easier to read.
What do you think?

Thanks,

Simon

>                 return NULL;
>         return a->palloc(a, order);
>   }
_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/minios-devel