static unsigned int udf_count_free_bitmap(struct super_block *sb,
					  struct udf_bitmap *bitmap)
{
	struct buffer_head *bh = NULL;
	unsigned int accum = 0;
	int index;
	int block = 0, newblock;
	struct kernel_lb_addr loc;
	uint32_t bytes;
	uint8_t *ptr;
	uint16_t ident;
	struct spaceBitmapDesc *bm;

	loc.logicalBlockNum = bitmap->s_extPosition;
	loc.partitionReferenceNum = UDF_SB(sb)->s_partition;
	bh = udf_read_ptagged(sb, &loc, 0, &ident);

	if (!bh) {
		udf_err(sb, "udf_count_free failed\n");
		goto out;
	} else if (ident != TAG_IDENT_SBD) {
		brelse(bh);
		udf_err(sb, "udf_count_free failed\n");
		goto out;
	}

	bm = (struct spaceBitmapDesc *)bh->b_data;
	bytes = le32_to_cpu(bm->numOfBytes);
	index = sizeof(struct spaceBitmapDesc); /* offset in first block only */
	ptr = (uint8_t *)bh->b_data;

	while (bytes > 0) {
		u32 cur_bytes = min_t(u32, bytes, sb->s_blocksize - index);
		accum += bitmap_weight((const unsigned long *)(ptr + index),
					cur_bytes * 8);
		bytes -= cur_bytes;
		if (bytes) {
			brelse(bh);
			newblock = udf_get_lb_pblock(sb, &loc, ++block);
			bh = udf_tread(sb, newblock);
			if (!bh) {
				udf_debug("read failed\n");
				goto out;
			}
			index = 0;
			ptr = (uint8_t *)bh->b_data;
		}
	}
	brelse(bh);
out:
	return accum;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.