linux-kernel - Re: [PATCH 1/1] Preventive patch in the proc file-system to handle NULL check.

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Date:   Thu, 16 Aug 2018 15:32:23 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Srikanth K H <srikanth.h@...sung.com>
Cc:     mcgrof@...nel.org, keescook@...omium.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/1] Preventive patch in the proc file-system to handle
 NULL check.

On Thu, Aug 16, 2018 at 03:04:13PM +0530, Srikanth K H wrote:
> If the make directory for "sys" interface fail's then its
> dereferenced without even checking for its validity which
> will lead to crash, hence added preventive code to check
> for NULL and accordingly dereference.

> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -1692,6 +1692,8 @@ int __init proc_sys_init(void)
>  	struct proc_dir_entry *proc_sys_root;
>  
>  	proc_sys_root = proc_mkdir("sys", NULL);
> +	if (!proc_sys_root)
> +		return -ENOMEM;
>  	proc_sys_root->proc_iops = &proc_sys_dir_operations;
>  	proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
>  	proc_sys_root->nlink = 0;

It is fine to crash because /proc is not modular.