Re: [PATCH] kasan: fix slab double free when cpu-hotplug

[Chris Down <chris@xxxxxxxxxxxxxx>]

Hi folks,

Andrew Morton writes:
> @@ -188,6 +190,10 @@ void quarantine_put(struct kasan_free_me
> 	local_irq_save(flags);
>
> 	q = this_cpu_ptr(&cpu_quarantine);
> +	if (q->offline) {
> +		local_irq_restore(flags);
> +		return;
> +	}
> 	qlist_put(q, &info->quarantine_link, cache->size);
> 	if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
> 		qlist_move_all(q, &temp);

I'm afraid as well as the issues already identified, this also fails, because 
`quarantine_put` now returns a bool after "kasan: sanitize objects when 
metadata doesn't fit":

    mm/kasan/quarantine.c: In function ‘quarantine_put’:
    mm/kasan/quarantine.c:198:3: error: ‘return’ with no value, in function returning non-void [-Werror=return-type]
      198 |   return;
          |   ^~~~~~
    mm/kasan/quarantine.c:171:6: note: declared here
      171 | bool quarantine_put(struct kmem_cache *cache, void *object)