linux-hardening - Re: [PATCH] drm/nouveau/pm: refactor deprecated strncpy

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Message-ID: <cf0f001fe5688d956c6a8521af494694377efb5b.camel@redhat.com>
Date:   Fri, 15 Sep 2023 13:34:41 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     Justin Stitt <justinstitt@...gle.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Karol Herbst <kherbst@...hat.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] drm/nouveau/pm: refactor deprecated strncpy

...oops, responded to the wrong email :P

Reviewed-by: Lyude Paul <lyude@...hat.com>


On Thu, 2023-09-14 at 22:17 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We should prefer more robust and less ambiguous string interfaces.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it guarantees
> NUL-termination on the destination buffer without unnecessarily NUL-padding.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> ---
>  drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c b/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c
> index 8fe0444f761e..131db2645f84 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c
> @@ -462,7 +462,7 @@ nvkm_perfmon_mthd_query_domain(struct nvkm_perfmon *perfmon,
>  
>  		args->v0.id         = di;
>  		args->v0.signal_nr  = nvkm_perfdom_count_perfsig(dom);
> -		strncpy(args->v0.name, dom->name, sizeof(args->v0.name) - 1);
> +		strscpy(args->v0.name, dom->name, sizeof(args->v0.name));
>  
>  		/* Currently only global counters (PCOUNTER) are implemented
>  		 * but this will be different for local counters (MP). */
> @@ -513,8 +513,7 @@ nvkm_perfmon_mthd_query_signal(struct nvkm_perfmon *perfmon,
>  			snprintf(args->v0.name, sizeof(args->v0.name),
>  				 "/%s/%02x", dom->name, si);
>  		} else {
> -			strncpy(args->v0.name, sig->name,
> -				sizeof(args->v0.name) - 1);
> +			strscpy(args->v0.name, sig->name, sizeof(args->v0.name));
>  		}
>  
>  		args->v0.signal = si;
> @@ -572,7 +571,7 @@ nvkm_perfmon_mthd_query_source(struct nvkm_perfmon *perfmon,
>  
>  		args->v0.source = sig->source[si];
>  		args->v0.mask   = src->mask;
> -		strncpy(args->v0.name, src->name, sizeof(args->v0.name) - 1);
> +		strscpy(args->v0.name, src->name, sizeof(args->v0.name));
>  	}
>  
>  	if (++si < source_nr) {
> 
> ---
> base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
> change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-engine-pm-base-c-38bf9c78bc0f
> 
> Best regards,
> --
> Justin Stitt <justinstitt@...gle.com>
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat