linux-kernel - Re: [PATCH] staging: vme_user: replace strcpy with strscpy

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Date:   Wed, 18 Oct 2023 13:17:25 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Calvince Otieno <calvncce@...il.com>
Cc:     gustavo@...eddedor.com, outreachy@...ts.linux.dev,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Martyn Welch <martyn@...chs.me.uk>,
        Manohar Vanga <manohar.vanga@...il.com>,
        Julia Lawall <julia.lawall@...ia.fr>,
        linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev
Subject: Re: [PATCH] staging: vme_user: replace strcpy with strscpy

On Wed, Oct 18, 2023 at 10:29:51AM +0300, Calvince Otieno wrote:
> Checkpatch suggests using strscpy() instead of strncpy().
> 
> The advantages of strscpy() are that it always adds a NUL terminator
> and prevents read overflows if the source string is not properly
> terminated. One potential disadvantage is that it doesn't zero pad the
> string like strncpy() does.

You're not replacing strncpy(), you're replacing strcpy().  There is
never a downside to replacing strcpy() with strspy() beyond that the
secure function is probably slightly slower.

> 
> In this code, strscpy() and strncpy() are equivalent and do not affect
> runtime behavior. strscpy() simply copies the known string value of the
> variable driver_name into the fake_bridge->name variable, which also
> has a fixed size.
> 
> While using strscpy() does not address any bugs, it is considered a better
> practice and aligns with checkpatch recommendations.

This analysis does not say where driver_name is set, or how big it is,
or what the size of the fake_bridge->name buffer is.  I would like to
see that sort of analysis in the commit message.

regards,
dan carpenter