perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
	struct frame_tail __user *tail;

	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
		/* We don't support guest os callchain now */
		return;
	}

	perf_callchain_store(entry, regs->ARM_pc);
	tail = (struct frame_tail __user *)regs->ARM_fp - 1;

	while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
	       tail && !((unsigned long)tail & 0x3))
		tail = user_backtrace(tail, entry);
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.