linux-hardening - Re: [PATCH v3] drivers/soc: Remove all strcpy() uses

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Date:   Sat, 7 Aug 2021 19:48:39 +0200
From:   Len Baker <len.baker@....com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Len Baker <len.baker@....com>, Kees Cook <keescook@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        David Laight <David.Laight@...lab.com>,
        Robin Murphy <robin.murphy@....com>,
        linux-hardening@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3] drivers/soc: Remove all strcpy() uses

Hi,

On Wed, Aug 04, 2021 at 05:23:54PM -0500, Bjorn Andersson wrote:
> On Sun 01 Aug 08:19 CDT 2021, Len Baker wrote:
>
> > strcpy() performs no bounds checking on the destination buffer. This
> > could result in linear overflows beyond the end of the buffer, leading
> > to all kinds of misbehaviors. The safe replacement is strscpy().
> >
>
> While this is true, are any of these uses of strcpy affected by its
> shortcomings?

No, this patch is only an effort to clean up the proliferation of str*()
functions in the kernel.

> > Moreover, when the size of the destination buffer cannot be obtained
> > using "sizeof", use the memcpy function instead of strscpy.
> >
>
> This is not why you're using memcpy, you're using it because you _know_
> how many bytes should be copied - because you just did a strlen() and
> allocated that amount of space.

Understood, I will change the commit message.

>
> > [...]
> >  		/* Prepare req message */
> > -		strcpy(req.service_path, pds->service_path);
> > +		strscpy(req.service_path, pds->service_path,
> > +			sizeof(req.service_path));
>
> There's no need to break this line.

Ok, thanks.

Regards,
Len