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Date: Tue, 28 Jan 2020 14:43:37 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Linux API <linux-api@vger.kernel.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	Linux Security Module <linux-security-module@vger.kernel.org>,
	Akinobu Mita <akinobu.mita@gmail.com>,
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Subject: Re: [PATCH v7 02/11] proc: add proc_fs_info struct to store proc
 information
Message-ID: <20200128134337.GC17943@redhat.com>
References: <20200125130541.450409-1-gladkov.alexey@gmail.com>
 <20200125130541.450409-3-gladkov.alexey@gmail.com>
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In-Reply-To: <20200125130541.450409-3-gladkov.alexey@gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23

On 01/25, Alexey Gladkov wrote:
>
>  static int proc_init_fs_context(struct fs_context *fc)
>  {
>  	struct proc_fs_context *ctx;
> +	struct pid_namespace *pid_ns;
>
>  	ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
>  	if (!ctx)
>  		return -ENOMEM;
>
> -	ctx->pid_ns = get_pid_ns(task_active_pid_ns(current));
> +	pid_ns = get_pid_ns(task_active_pid_ns(current));
> +
> +	if (!pid_ns->proc_mnt) {
> +		ctx->fs_info = kzalloc(sizeof(struct proc_fs_info), GFP_KERNEL);
> +		if (!ctx->fs_info) {
> +			kfree(ctx);
> +			return -ENOMEM;
> +		}
> +		ctx->fs_info->pid_ns = pid_ns;
> +	} else {
> +		ctx->fs_info = proc_sb_info(pid_ns->proc_mnt->mnt_sb);
> +	}
> +

it seems that this code lacks put_pid_ns() if pid_ns->proc_mnt != NULL
or if kzalloc() fails?

Or, better,

	pid_ns = task_active_pid_ns();

	if (!pid_ns->proc_mnt) {
		ctx->fs_info = kzalloc();
		...
		ctx->fs_info->pid_ns = get_pid_ns(pid_ns);
	}

No?

Oleg.