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

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Date:   Wed, 18 Oct 2023 09:39:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Calvince Otieno <calvncce@...il.com>
Cc:     gustavo@...eddedor.com, outreachy@...ts.linux.dev,
        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.
> 
> 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.
> 
> Signed-off-by: Calvince Otieno <calvncce@...il.com>
> ---
>  drivers/staging/vme_user/vme_fake.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/vme_user/vme_fake.c b/drivers/staging/vme_user/vme_fake.c
> index 0e02c194298d..09b05861017a 100644
> --- a/drivers/staging/vme_user/vme_fake.c
> +++ b/drivers/staging/vme_user/vme_fake.c
> @@ -67,6 +67,7 @@ struct fake_driver {
>  	unsigned long long lm_base;
>  	u32 lm_aspace;
>  	u32 lm_cycle;
> +
>  	void (*lm_callback[4])(void *);
>  	void *lm_data[4];

Why did you make this extra line change?

>  	struct tasklet_struct int_tasklet;
> @@ -1091,7 +1092,7 @@ static int __init fake_init(void)
>  	tasklet_init(&fake_device->int_tasklet, fake_VIRQ_tasklet,
>  		     (unsigned long)fake_bridge);
>  
> -	strcpy(fake_bridge->name, driver_name);
> +	strscpy(fake_bridge->name, driver_name, sizeof(fake_bridge->name))

Are you sure this change is identical?  You need to document how you
have proved that.

thanks,

greg k-h