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Date: Thu, 16 Jun 2016 08:08:22 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Willy Tarreau <w@1wt.eu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Andy Lutomirski <luto@kernel.org>,
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Subject: Re: [PATCH v2 1/2] fs: Improve and simplify copy_mount_options
Message-ID: <20160616070821.GB14480@ZenIV.linux.org.uk>
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On Thu, Jun 16, 2016 at 08:57:38AM +0200, Willy Tarreau wrote:
> +	type = get_fs_type(fstype);
> +	if (!type)
> +		return NULL;
> +
>  	copy = kmalloc(PAGE_SIZE, GFP_KERNEL);
>  	if (!copy)
>  		return ERR_PTR(-ENOMEM);
>  
> +	/* avoid reading a whole page if the FS only needs a string. */
> +	if (!(type->fs_flags & FS_BINARY_MOUNTDATA)) {
> +		strlcpy(copy, data, PAGE_SIZE);
> +		return copy;

a) it leaks a file_system_type reference
b) data is a userland pointer, for crying out loud!