linux-kernel - Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf

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Message-ID: <202205231238.FAF6D28@keescook>
Date:   Mon, 23 May 2022 12:39:12 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Maninder Singh <maninder1.s@...sung.com>, pmladek@...e.com,
        bcain@...cinc.com, mpe@...erman.id.au, benh@...nel.crashing.org,
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Subject: Re: [PATCH 0/5] kallsyms: make kallsym APIs more safe with scnprintf

On Sat, May 21, 2022 at 11:07:52PM -0700, Christoph Hellwig wrote:
> On Fri, May 20, 2022 at 02:06:56PM +0530, Maninder Singh wrote:
> > kallsyms functionality depends on KSYM_NAME_LEN directly.
> > but if user passed array length lesser than it, sprintf
> > can cause issues of buffer overflow attack.
> > 
> > So changing *sprint* and *lookup* APIs in this patch set
> > to have buffer size as an argument and replacing sprintf with
> > scnprintf.
> 
> This is still a pretty horrible API.  Passing something like
> a struct seq_buf seems like the much better API here.  Also with
> the amount of arguments and by reference passing it might be worth
> to pass them as a structure while you're at it.

Yeah, I agree. It really seems like seq_buf would be nicer.

-- 
Kees Cook