Re: [PATCH v3 2/7] tpm: Replace the dynamically allocated bios_dir as struct dentry array.

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Tue, Aug 30, 2016 at 12:50:14AM -0400, Nayna Jain wrote:
> bios_dir is defined as struct dentry **bios_dir, which results in
> dynamic allocation and possible memory leak. This patch replaces
> it with struct dentry array i.e. struct dentry *bios_dir[3]
> similar to what is done for sysfs groups.
> 
> Suggested-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
> Signed-off-by: Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> ---
>  drivers/char/tpm/tpm-chip.c     |  5 ++--
>  drivers/char/tpm/tpm.h          |  3 ++-
>  drivers/char/tpm/tpm_eventlog.c | 60 ++++++++++++++++++-----------------------
>  drivers/char/tpm/tpm_eventlog.h | 10 +++----
>  4 files changed, 35 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index e595013..1cd1238 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -283,7 +283,7 @@ static int tpm1_chip_register(struct tpm_chip *chip)
>  
>  	tpm_sysfs_add_device(chip);
>  
> -	chip->bios_dir = tpm_bios_log_setup(dev_name(&chip->dev));
> +	tpm_bios_log_setup(chip);
>  
>  	return 0;
>  }
> @@ -293,8 +293,7 @@ static void tpm1_chip_unregister(struct tpm_chip *chip)
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2)
>  		return;
>  
> -	if (chip->bios_dir)
> -		tpm_bios_log_teardown(chip->bios_dir);
> +	tpm_bios_log_teardown(chip);
>  }
>  
>  static void tpm_del_legacy_sysfs(struct tpm_chip *chip)
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 6e002c4..603a661 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -171,7 +171,8 @@ struct tpm_chip {
>  	unsigned long duration[3]; /* jiffies */
>  	bool duration_adjusted;
>  
> -	struct dentry **bios_dir;
> +	struct dentry *bios_dir[3];
> +	unsigned int bios_dir_count;


Do this without bios_dir_count with a four element array. Last idex is
the NULL terminator.

>  	const struct attribute_group *groups[3];
>  	unsigned int groups_cnt;
> diff --git a/drivers/char/tpm/tpm_eventlog.c b/drivers/char/tpm/tpm_eventlog.c
> index b0a4d02..9dd69a7 100644
> --- a/drivers/char/tpm/tpm_eventlog.c
> +++ b/drivers/char/tpm/tpm_eventlog.c
> @@ -332,7 +332,8 @@ static int tpm_bios_measurements_open(struct inode *inode,
>  	if (!log)
>  		return -ENOMEM;
>  
> -	if ((err = read_log(log)))
> +	err = read_log(log);
> +	if (err)
>  		goto out_free;
>  
>  	/* now register seq file */
> @@ -368,54 +369,45 @@ static int is_bad(void *p)
>  	return 0;
>  }
>  
> -struct dentry **tpm_bios_log_setup(const char *name)
> +void tpm_bios_log_setup(struct tpm_chip *chip)
>  {
> -	struct dentry **ret = NULL, *tpm_dir, *bin_file, *ascii_file;
> +	const char *name = dev_name(&chip->dev);
>  
> -	tpm_dir = securityfs_create_dir(name, NULL);
> -	if (is_bad(tpm_dir))
> -		goto out;
> +	chip->bios_dir_count = 0;
> +	chip->bios_dir[chip->bios_dir_count] = securityfs_create_dir(name,
> +	NULL);
> +	if (is_bad(chip->bios_dir[chip->bios_dir_count]))
> +		goto err;
> +	chip->bios_dir_count++;
>  
> -	bin_file =
> +	chip->bios_dir[chip->bios_dir_count] =
>  	    securityfs_create_file("binary_bios_measurements",
> -				   S_IRUSR | S_IRGRP, tpm_dir,
> +				   S_IRUSR | S_IRGRP, chip->bios_dir[0],
>  				   (void *)&tpm_binary_b_measurments_seqops,
>  				   &tpm_bios_measurements_ops);
> -	if (is_bad(bin_file))
> -		goto out_tpm;
> +	if (is_bad(chip->bios_dir[chip->bios_dir_count]))
> +		goto err;
> +	chip->bios_dir_count++;
>  
> -	ascii_file =
> +	chip->bios_dir[chip->bios_dir_count] =
>  	    securityfs_create_file("ascii_bios_measurements",
> -				   S_IRUSR | S_IRGRP, tpm_dir,
> +				   S_IRUSR | S_IRGRP, chip->bios_dir[0],
>  				   (void *)&tpm_ascii_b_measurments_seqops,
>  				   &tpm_bios_measurements_ops);
> -	if (is_bad(ascii_file))
> -		goto out_bin;
> +	if (is_bad(chip->bios_dir[chip->bios_dir_count]))
> +		goto err;
> +	chip->bios_dir_count++;
>  
> -	ret = kmalloc(3 * sizeof(struct dentry *), GFP_KERNEL);
> -	if (!ret)
> -		goto out_ascii;
> +	return;
>  
> -	ret[0] = ascii_file;
> -	ret[1] = bin_file;
> -	ret[2] = tpm_dir;
> -
> -	return ret;
> -
> -out_ascii:
> -	securityfs_remove(ascii_file);
> -out_bin:
> -	securityfs_remove(bin_file);
> -out_tpm:
> -	securityfs_remove(tpm_dir);
> -out:
> -	return NULL;
> +err:
> +	tpm_bios_log_teardown(chip);
>  }
>  
> -void tpm_bios_log_teardown(struct dentry **lst)
> +void tpm_bios_log_teardown(struct tpm_chip *chip)
>  {
>  	int i;
>  
> -	for (i = 0; i < 3; i++)
> -		securityfs_remove(lst[i]);
> +	for (i = chip->bios_dir_count; i > 0; --i)
> +		securityfs_remove(chip->bios_dir[i-1]);

Are you doing this to somehow "optimize"? If the answer is yes, please
don't do it. Just loop from zero.

Anyway with NULL terminated array:

for (i = 0; chip->bios_dir[i] != NULL; i++)

>  }
> diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
> index 8de62b0..67621c9 100644
> --- a/drivers/char/tpm/tpm_eventlog.h
> +++ b/drivers/char/tpm/tpm_eventlog.h
> @@ -77,14 +77,14 @@ int read_log(struct tpm_bios_log *log);
>  
>  #if defined(CONFIG_TCG_IBMVTPM) || defined(CONFIG_TCG_IBMVTPM_MODULE) || \
>  	defined(CONFIG_ACPI)
> -extern struct dentry **tpm_bios_log_setup(const char *);
> -extern void tpm_bios_log_teardown(struct dentry **);
> +extern void tpm_bios_log_setup(struct tpm_chip *chip);
> +extern void tpm_bios_log_teardown(struct tpm_chip *chip);
>  #else
> -static inline struct dentry **tpm_bios_log_setup(const char *name)
> +static inline void tpm_bios_log_setup(struct tpm_chip *chip)
>  {
> -	return NULL;
> +	chip->bios_dir_count = 0;
>  }
> -static inline void tpm_bios_log_teardown(struct dentry **dir)
> +static inline void tpm_bios_log_teardown(struct tpm_chip *chip)
>  {
>  }
>  #endif
> -- 
> 2.5.0
> 
> 
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/Jarkko

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