void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
{
	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
	struct list_head *head = &dcc->entry_list;
	struct discard_entry *entry, *this;
	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
	unsigned long *prefree_map = dirty_i->dirty_segmap[PRE];
	unsigned int start = 0, end = -1;
	unsigned int secno, start_segno;
	bool force = (cpc->reason & CP_DISCARD);

	mutex_lock(&dirty_i->seglist_lock);

	while (1) {
		int i;
		start = find_next_bit(prefree_map, MAIN_SEGS(sbi), end + 1);
		if (start >= MAIN_SEGS(sbi))
			break;
		end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
								start + 1);

		for (i = start; i < end; i++)
			clear_bit(i, prefree_map);

		dirty_i->nr_dirty[PRE] -= end - start;

		if (!test_opt(sbi, DISCARD))
			continue;

		if (force && start >= cpc->trim_start &&
					(end - 1) <= cpc->trim_end)
				continue;

		if (!test_opt(sbi, LFS) || sbi->segs_per_sec == 1) {
			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
				(end - start) << sbi->log_blocks_per_seg);
			continue;
		}
next:
		secno = GET_SEC_FROM_SEG(sbi, start);
		start_segno = GET_SEG_FROM_SEC(sbi, secno);
		if (!IS_CURSEC(sbi, secno) &&
			!get_valid_blocks(sbi, start, true))
			f2fs_issue_discard(sbi, START_BLOCK(sbi, start_segno),
				sbi->segs_per_sec << sbi->log_blocks_per_seg);

		start = start_segno + sbi->segs_per_sec;
		if (start < end)
			goto next;
		else
			end = start - 1;
	}
	mutex_unlock(&dirty_i->seglist_lock);

	/* send small discards */
	list_for_each_entry_safe(entry, this, head, list) {
		unsigned int cur_pos = 0, next_pos, len, total_len = 0;
		bool is_valid = test_bit_le(0, entry->discard_map);

find_next:
		if (is_valid) {
			next_pos = find_next_zero_bit_le(entry->discard_map,
					sbi->blocks_per_seg, cur_pos);
			len = next_pos - cur_pos;

			if (f2fs_sb_mounted_blkzoned(sbi->sb) ||
			    (force && len < cpc->trim_minlen))
				goto skip;

			f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos,
									len);
			cpc->trimmed += len;
			total_len += len;
		} else {
			next_pos = find_next_bit_le(entry->discard_map,
					sbi->blocks_per_seg, cur_pos);
		}
skip:
		cur_pos = next_pos;
		is_valid = !is_valid;

		if (cur_pos < sbi->blocks_per_seg)
			goto find_next;

		list_del(&entry->list);
		dcc->nr_discards -= total_len;
		kmem_cache_free(discard_entry_slab, entry);
	}

	wake_up_discard_thread(sbi, false);
}

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.