linux-kernel - Re: [PATCH v2 1/2] tpm: Use managed allocation for bios event log

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Message-ID: <ea8e873f-c052-832f-b4a5-0164f5cd6947@linux.ibm.com>
Date:   Wed, 25 Jan 2023 13:06:31 -0600
From:   Eddie James <eajames@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jgg@...pe.ca, peterhuewe@....de
Subject: Re: [PATCH v2 1/2] tpm: Use managed allocation for bios event log


On 1/20/23 18:11, Jarkko Sakkinen wrote:
> On Fri, Jan 13, 2023 at 10:10:16AM -0600, Eddie James wrote:
>> Since the bios event log is freed in the device release function,
>> let devres handle the deallocation. This will allow other memory
>> allocation/mapping functions to be used for the bios event log.
>>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> ---
>>   drivers/char/tpm/eventlog/acpi.c |  5 +++--
>>   drivers/char/tpm/eventlog/efi.c  | 13 +++++++------
>>   drivers/char/tpm/eventlog/of.c   |  3 ++-
>>   drivers/char/tpm/tpm-chip.c      |  1 -
>>   4 files changed, 12 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
>> index 0913d3eb8d51..40360e599bc3 100644
>> --- a/drivers/char/tpm/eventlog/acpi.c
>> +++ b/drivers/char/tpm/eventlog/acpi.c
>> @@ -14,6 +14,7 @@
>>    * Access to the event log extended by the TCG BIOS of PC platform
>>    */
>>   
>> +#include <linux/device.h>
>>   #include <linux/seq_file.h>
>>   #include <linux/fs.h>
>>   #include <linux/security.h>
>> @@ -135,7 +136,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>>   	}
>>   
>>   	/* malloc EventLog space */
>> -	log->bios_event_log = kmalloc(len, GFP_KERNEL);
>> +	log->bios_event_log = devm_kmalloc(&chip->dev, len, GFP_KERNEL);
>>   	if (!log->bios_event_log)
>>   		return -ENOMEM;
>>   
>> @@ -160,7 +161,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>>   	return format;
>>   
>>   err:
>> -	kfree(log->bios_event_log);
>> +	devm_kfree(&chip->dev, log->bios_event_log);
> I wonder do we want to do devm_kfree's at all as the memory is freed during
> detach, i.e. taken care by devres.


I think we should since the chip/tpm driver will continue to probe 
without the bios event log. Therefore that memory will be wasted if 
there is some error during bios log setup.


Thanks,

Eddie


>
>>   	log->bios_event_log = NULL;
>>   	return ret;
>>   }
>> diff --git a/drivers/char/tpm/eventlog/efi.c b/drivers/char/tpm/eventlog/efi.c
>> index e6cb9d525e30..4e9d7c2bf32e 100644
>> --- a/drivers/char/tpm/eventlog/efi.c
>> +++ b/drivers/char/tpm/eventlog/efi.c
>> @@ -6,6 +6,7 @@
>>    *      Thiebaud Weksteen <tweek@...gle.com>
>>    */
>>   
>> +#include <linux/device.h>
>>   #include <linux/efi.h>
>>   #include <linux/tpm_eventlog.h>
>>   
>> @@ -55,7 +56,7 @@ int tpm_read_log_efi(struct tpm_chip *chip)
>>   	}
>>   
>>   	/* malloc EventLog space */
>> -	log->bios_event_log = kmemdup(log_tbl->log, log_size, GFP_KERNEL);
>> +	log->bios_event_log = devm_kmemdup(&chip->dev, log_tbl->log, log_size, GFP_KERNEL);
>>   	if (!log->bios_event_log) {
>>   		ret = -ENOMEM;
>>   		goto out;
>> @@ -76,7 +77,7 @@ int tpm_read_log_efi(struct tpm_chip *chip)
>>   			     MEMREMAP_WB);
>>   	if (!final_tbl) {
>>   		pr_err("Could not map UEFI TPM final log\n");
>> -		kfree(log->bios_event_log);
>> +		devm_kfree(&chip->dev, log->bios_event_log);
>>   		ret = -ENOMEM;
>>   		goto out;
>>   	}
>> @@ -91,11 +92,11 @@ int tpm_read_log_efi(struct tpm_chip *chip)
>>   	 * Allocate memory for the 'combined log' where we will append the
>>   	 * 'final events log' to.
>>   	 */
>> -	tmp = krealloc(log->bios_event_log,
>> -		       log_size + final_events_log_size,
>> -		       GFP_KERNEL);
>> +	tmp = devm_krealloc(&chip->dev, log->bios_event_log,
>> +			    log_size + final_events_log_size,
>> +			    GFP_KERNEL);
>>   	if (!tmp) {
>> -		kfree(log->bios_event_log);
>> +		devm_kfree(&chip->dev, log->bios_event_log);
>>   		ret = -ENOMEM;
>>   		goto out;
>>   	}
>> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
>> index a9ce66d09a75..741ab2204b11 100644
>> --- a/drivers/char/tpm/eventlog/of.c
>> +++ b/drivers/char/tpm/eventlog/of.c
>> @@ -10,6 +10,7 @@
>>    * Read the event log created by the firmware on PPC64
>>    */
>>   
>> +#include <linux/device.h>
>>   #include <linux/slab.h>
>>   #include <linux/of.h>
>>   #include <linux/tpm_eventlog.h>
>> @@ -65,7 +66,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
>>   		return -EIO;
>>   	}
>>   
>> -	log->bios_event_log = kmemdup(__va(base), size, GFP_KERNEL);
>> +	log->bios_event_log = devm_kmemdup(&chip->dev, __va(base), size, GFP_KERNEL);
>>   	if (!log->bios_event_log)
>>   		return -ENOMEM;
>>   
>> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
>> index 741d8f3e8fb3..b99f55f2d4fd 100644
>> --- a/drivers/char/tpm/tpm-chip.c
>> +++ b/drivers/char/tpm/tpm-chip.c
>> @@ -267,7 +267,6 @@ static void tpm_dev_release(struct device *dev)
>>   	idr_remove(&dev_nums_idr, chip->dev_num);
>>   	mutex_unlock(&idr_lock);
>>   
>> -	kfree(chip->log.bios_event_log);
>>   	kfree(chip->work_space.context_buf);
>>   	kfree(chip->work_space.session_buf);
>>   	kfree(chip->allocated_banks);
>> -- 
>> 2.31.1
>>
> BR, Jarkko