int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,
			int var,
			snd_pcm_hw_rule_func_t func, void *private,
			int dep, ...)
{
	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
	struct snd_pcm_hw_rule *c;
	unsigned int k;
	va_list args;
	va_start(args, dep);
	if (constrs->rules_num >= constrs->rules_all) {
		struct snd_pcm_hw_rule *new;
		unsigned int new_rules = constrs->rules_all + 16;
		new = kcalloc(new_rules, sizeof(*c), GFP_KERNEL);
		if (!new) {
			va_end(args);
			return -ENOMEM;
		}
		if (constrs->rules) {
			memcpy(new, constrs->rules,
			       constrs->rules_num * sizeof(*c));
			kfree(constrs->rules);
		}
		constrs->rules = new;
		constrs->rules_all = new_rules;
	}
	c = &constrs->rules[constrs->rules_num];
	c->cond = cond;
	c->func = func;
	c->var = var;
	c->private = private;
	k = 0;
	while (1) {
		if (snd_BUG_ON(k >= ARRAY_SIZE(c->deps))) {
			va_end(args);
			return -EINVAL;
		}
		c->deps[k++] = dep;
		if (dep < 0)
			break;
		dep = va_arg(args, int);
	}
	constrs->rules_num++;
	va_end(args);
	return 0;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.