linux-kernel - Re: [PATCH] tpm: Fix memory leak in tpmm_chip

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Date:   Mon, 14 Mar 2022 13:37:05 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     GUO Zihua <guozihua@...wei.com>
Cc:     linux-integrity@...r.kernel.org, wangweiyang2@...wei.com,
        xiujianfeng@...wei.com, weiyongjun1@...wei.com, peterhuewe@....de,
        jarkko@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: Fix memory leak in tpmm_chip_alloc

On Mon, Mar 07, 2022 at 06:48:27PM +0800, GUO Zihua wrote:
> Fix a memory leak in tpmm_chip_alloc. devm_add_action_or_reset would
> call put_device on error, while tpm->devs is left untouched. Call
> put_device on tpm->devs as well if devm_add_action_or_reset returns an
> error.
> 
> Fixes: fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm")
> Signed-off-by: GUO Zihua <guozihua@...wei.com>
>  drivers/char/tpm/tpm-chip.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index b009e7479b70..0a92334e8c40 100644
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -308,6 +308,12 @@ static int tpm_class_shutdown(struct device *dev)
>  	return 0;
>  }
>  
> +static void tpm_chip_free(struct tpm_chip *chip)
> +{
> +	put_device(&chip->devs);
> +	put_device(&chip->dev);
> +}
> +
>  /**
>   * tpm_chip_alloc() - allocate a new struct tpm_chip instance
>   * @pdev: device to which the chip is associated
> @@ -396,8 +402,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>  	return chip;
>  
>  out:
> -	put_device(&chip->devs);
> -	put_device(&chip->dev);
> +	tpm_chip_free(chip);
>  	return ERR_PTR(rc);
>  }
>  EXPORT_SYMBOL_GPL(tpm_chip_alloc);
> @@ -420,8 +425,8 @@ struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
>  		return chip;
>  
>  	rc = devm_add_action_or_reset(pdev,
> -				      (void (*)(void *)) put_device,
> -				      &chip->dev);
> +				      (void (*)(void *)) tpm_chip_free,
> +				      chip);
>  	if (rc)

This looks like the same issue as was adressed by the recent discussion..

Jason