linux-kernel - Re: [PATCH v4 1/1] x86/sgx: Enable automatic SVN updates for SGX enclaves

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Message-ID: <aB0QZP4Mi4hydNSx@kernel.org>
Date: Thu, 8 May 2025 23:13:24 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Elena Reshetova <elena.reshetova@...el.com>
Cc: dave.hansen@...el.com, seanjc@...gle.com, kai.huang@...el.com,
	linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, asit.k.mallick@...el.com,
	vincent.r.scarlata@...el.com, chongc@...gle.com,
	erdemaktas@...gle.com, vannapurve@...gle.com,
	dionnaglaze@...gle.com, bondarn@...gle.com, scott.raynor@...el.com
Subject: Re: [PATCH v4 1/1] x86/sgx: Enable automatic SVN updates for SGX
 enclaves

On Wed, May 07, 2025 at 02:14:00PM +0300, Elena Reshetova wrote:
  
> diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
> index 7f8d1e11dbee..669e44d61f9f 100644
> --- a/arch/x86/kernel/cpu/sgx/driver.c
> +++ b/arch/x86/kernel/cpu/sgx/driver.c
> @@ -19,6 +19,10 @@ static int sgx_open(struct inode *inode, struct file *file)
>  	struct sgx_encl *encl;
>  	int ret;
>  
> +	ret = sgx_inc_usage_count();
> +	if (ret)
> +		return ret;
> +
>  	encl = kzalloc(sizeof(*encl), GFP_KERNEL);
>  	if (!encl)
>  		return -ENOMEM;

The rollback looks broken to me.

Let's clean up error handling a bit:

	encl = kzalloc(sizeof(*encl), GFP_KERNEL);
	if (!encl) {
		ret = -ENOMEM;
		goto err_usage_count;
	}

And later on in the same function:

	ret = init_srcu_struct(&encl->srcu);
	if (ret)
		goto err_encl;

And finally tail:

	return 0;

err_encl:
	kfree(encl);

err_usage_count:
	sgx_dec_usage_count();
	return ret;
}

BR, Jarkko