Re: [PATCH] randread: unitialized memory fix

[Pádraig Brady]

On 21/09/2021 15:40, Mikhail Barashkov via GNU coreutils General Discussion 
wrote:
> Randread was allocating memory, but not setting it to 0, resulting, in
> particular, to a crash in shuf program in E2K CPU protected mode (later
> on s->bug is used by shuf in ISAAC_MIX as the seed parameter).
>
> This patch makes sure the memory buffer is zeroed out correctly.
>
> diff --git a/gl/lib/randread.c b/gl/lib/randread.c
> index 7124e3df0..8e6b1c5b8 100644
> --- a/gl/lib/randread.c
> +++ b/gl/lib/randread.c
> @@ -132,6 +132,7 @@ static struct randread_source *
>    simple_new (FILE *source, void const *handler_arg)
>    {
>      struct randread_source *s = xmalloc (sizeof *s);
> +  memset(s, 0, sizeof *s);
>      s->source = source;
>      s->handler = randread_error;
>      s->handler_arg = handler_arg;

I'm wary of the unconditional initialization of this large struct here.
I'm reminded of this general discussion https://research.swtch.com/sparse

If __e2k__ needs this, we should probably restrict to that arch?
Also should you be using xcalloc(1, sizeof *s) instead?

I'll let Paul review this as he's most familiar with this code.

cheers,
Pádraig