int exfat_mount(struct exfat* ef, const char* spec, const char* options)
{
	int rc;
	enum exfat_mode mode;

	exfat_tzset();
	memset(ef, 0, sizeof(struct exfat));

	parse_options(ef, options);

	if (match_option(options, "ro"))
		mode = EXFAT_MODE_RO;
	else if (match_option(options, "ro_fallback"))
		mode = EXFAT_MODE_ANY;
	else
		mode = EXFAT_MODE_RW;
	ef->dev = exfat_open(spec, mode);
	if (ef->dev == NULL)
		return -EIO;
	if (exfat_get_mode(ef->dev) == EXFAT_MODE_RO)
	{
		if (mode == EXFAT_MODE_ANY)
			ef->ro = -1;
		else
			ef->ro = 1;
	}

	ef->sb = malloc(sizeof(struct exfat_super_block));
	if (ef->sb == NULL)
	{
		exfat_close(ef->dev);
		exfat_error("failed to allocate memory for the super block");
		return -ENOMEM;
	}
	memset(ef->sb, 0, sizeof(struct exfat_super_block));

	if (exfat_pread(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
	{
		exfat_close(ef->dev);
		free(ef->sb);
		exfat_error("failed to read boot sector");
		return -EIO;
	}
	if (memcmp(ef->sb->oem_name, "EXFAT   ", 8) != 0)
	{
		exfat_close(ef->dev);
		free(ef->sb);
 		exfat_error("exFAT file system is not found");
 		return -EIO;
 	}
 	ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
 	if (ef->zero_cluster == NULL)
 	{
		exfat_close(ef->dev);
		free(ef->sb);
		exfat_error("failed to allocate zero sector");
		return -ENOMEM;
	}
	/* use zero_cluster as a temporary buffer for VBR checksum verification */
	if (!verify_vbr_checksum(ef->dev, ef->zero_cluster, SECTOR_SIZE(*ef->sb)))
	{
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		free(ef->sb);
		return -EIO;
	}
	memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
	if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
	{
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		exfat_error("unsupported exFAT version: %hhu.%hhu",
				ef->sb->version.major, ef->sb->version.minor);
		free(ef->sb);
		return -EIO;
	}
	if (ef->sb->fat_count != 1)
	{
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
 		free(ef->sb);
 		return -EIO;
 	}
	/* officially exFAT supports cluster size up to 32 MB */
	if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
	{
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		exfat_error("too big cluster size: 2^%d",
				(int) ef->sb->sector_bits + (int) ef->sb->spc_bits);
		free(ef->sb);
		return -EIO;
	}
 	if (le64_to_cpu(ef->sb->sector_count) * SECTOR_SIZE(*ef->sb) >
 			exfat_get_size(ef->dev))
 	{
		/* this can cause I/O errors later but we don't fail mounting to let
		   user rescue data */
		exfat_warn("file system is larger than underlying device: "
				"%"PRIu64" > %"PRIu64,
				le64_to_cpu(ef->sb->sector_count) * SECTOR_SIZE(*ef->sb),
				exfat_get_size(ef->dev));
	}

	ef->root = malloc(sizeof(struct exfat_node));
	if (ef->root == NULL)
	{
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		free(ef->sb);
		exfat_error("failed to allocate root node");
		return -ENOMEM;
	}
	memset(ef->root, 0, sizeof(struct exfat_node));
	ef->root->flags = EXFAT_ATTRIB_DIR;
	ef->root->start_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
	ef->root->fptr_cluster = ef->root->start_cluster;
	ef->root->name[0] = cpu_to_le16('\0');
	ef->root->size = rootdir_size(ef);
	if (ef->root->size == 0)
	{
		free(ef->root);
		free(ef->zero_cluster);
		exfat_close(ef->dev);
		free(ef->sb);
		return -EIO;
	}
	/* exFAT does not have time attributes for the root directory */
	ef->root->mtime = 0;
	ef->root->atime = 0;
	/* always keep at least 1 reference to the root node */
	exfat_get_node(ef->root);

	rc = exfat_cache_directory(ef, ef->root);
	if (rc != 0)
		goto error;
	if (ef->upcase == NULL)
	{
		exfat_error("upcase table is not found");
		goto error;
	}
	if (ef->cmap.chunk == NULL)
	{
		exfat_error("clusters bitmap is not found");
		goto error;
	}

	if (prepare_super_block(ef) != 0)
		goto error;

	return 0;

error:
	exfat_put_node(ef, ef->root);
	exfat_reset_cache(ef);
	free(ef->root);
	free(ef->zero_cluster);
	exfat_close(ef->dev);
	free(ef->sb);
	return -EIO;
}

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.