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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id 17-20020a170902ee5100b001bdc209b9a0sm2400126plo.201.2023.09.14.21.33.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Sep 2023 21:33:26 -0700 (PDT) Date: Thu, 14 Sep 2023 21:33:25 -0700 From: Kees Cook To: Justin Stitt Cc: Lucas Stach , Russell King , Christian Gmeiner , David Airlie , Daniel Vetter , etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Bo YU Subject: Re: [PATCH] drm/etnaviv: refactor deprecated strncpy Message-ID: <202309142133.F7FBDD9@keescook> References: <20230914-strncpy-drivers-gpu-drm-etnaviv-etnaviv_perfmon-c-v1-1-3adc2d9bfc52@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230914-strncpy-drivers-gpu-drm-etnaviv-etnaviv_perfmon-c-v1-1-3adc2d9bfc52@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 14, 2023 at 06:20:01PM +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. > > 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@vger.kernel.org > Cc: Bo YU > Signed-off-by: Justin Stitt > --- > Similar to [1] which was never picked up. Let's prefer strscpy to strlcpy, though > > [1]: https://lore.kernel.org/all/20190328080918.9290-1-tsu.yubo@gmail.com/ > --- > drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c > index bafdfe49c1d8..9e7bebcf24eb 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c > @@ -511,7 +511,7 @@ int etnaviv_pm_query_dom(struct etnaviv_gpu *gpu, > > domain->id = domain->iter; > domain->nr_signals = dom->nr_signals; > - strncpy(domain->name, dom->name, sizeof(domain->name)); > + strscpy(domain->name, dom->name, sizeof(domain->name)); It looks like this is passing through an ioctl(). Let's use strscpy_pad(0 instead... -Kees > > domain->iter++; > if (domain->iter == nr_domains) > @@ -540,7 +540,7 @@ int etnaviv_pm_query_sig(struct etnaviv_gpu *gpu, > sig = &dom->signal[signal->iter]; > > signal->id = signal->iter; > - strncpy(signal->name, sig->name, sizeof(signal->name)); > + strscpy(signal->name, sig->name, sizeof(signal->name)); > > signal->iter++; > if (signal->iter == dom->nr_signals) > > --- > base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec > change-id: 20230914-strncpy-drivers-gpu-drm-etnaviv-etnaviv_perfmon-c-dd095491dfde > > Best regards, > -- > Justin Stitt > -- Kees Cook