Re: [PATCH] proc: fix to check name length in proc_lookup_de()

[Alexey Dobriyan <adobriyan@gmail.com>]

On Tue, Jan 10, 2023 at 11:21:12PM +0800, Chao Yu wrote:
> __proc_create() has limited dirent's max name length with 255, let's
> add this limitation in proc_lookup_de(), so that it can return
> -ENAMETOOLONG correctly instead of -ENOENT when stating a file which
> has out-of-range name length.

Both returns are correct and this is trading one errno for another.

> --- a/fs/proc/generic.c
> +++ b/fs/proc/generic.c
> @@ -246,6 +246,9 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
>  {
>  	struct inode *inode;
>  
> +	if (dentry->d_name.len > PROC_NAME_LEN)
> +		return ERR_PTR(-ENAMETOOLONG);