linux-hardening - [PATCH v2] drm/etnaviv: refactor deprecated strncpy

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Message-ID: <20230918-strncpy-drivers-gpu-drm-etnaviv-etnaviv_perfmon-c-v2-1-8ae12071c138@google.com>
Date:   Mon, 18 Sep 2023 13:34:08 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     etnaviv@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
        Bo YU <tsu.yubo@...il.com>,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH v2] drm/etnaviv: refactor deprecated strncpy

`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_pad` due to the fact that it
guarantees NUL-termination on the destination buffer whilst maintaining
the NUL-padding behavior that strncpy provides.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Cc: Bo YU <tsu.yubo@...il.com>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Changes in v2:
- use strscpy_pad (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-gpu-drm-etnaviv-etnaviv_perfmon-c-v1-1-3adc2d9bfc52@google.com
---
Similar to [2] which was never picked up. Let's prefer strscpy_pad to strlcpy, though

[2]: 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..dc9dea664a28 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_pad(domain->name, dom->name, sizeof(domain->name));
 
 	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_pad(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 <justinstitt@...gle.com>