* [PATCH] drm/nouveau/pm: refactor deprecated strncpy
@ 2023-09-14 22:17 Justin Stitt
2023-09-15 4:59 ` Kees Cook
2023-09-15 17:34 ` Lyude Paul
0 siblings, 2 replies; 4+ messages in thread
From: Justin Stitt @ 2023-09-14 22:17 UTC (permalink / raw)
To: Ben Skeggs, Karol Herbst, Lyude Paul, David Airlie, Daniel Vetter
Cc: dri-devel, nouveau, linux-kernel, linux-hardening, Justin Stitt
`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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.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@google.com>
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] drm/nouveau/pm: refactor deprecated strncpy
2023-09-14 22:17 [PATCH] drm/nouveau/pm: refactor deprecated strncpy Justin Stitt
@ 2023-09-15 4:59 ` Kees Cook
2023-09-15 17:32 ` Lyude Paul
2023-09-15 17:34 ` Lyude Paul
1 sibling, 1 reply; 4+ messages in thread
From: Kees Cook @ 2023-09-15 4:59 UTC (permalink / raw)
To: Justin Stitt
Cc: Ben Skeggs, Karol Herbst, Lyude Paul, David Airlie, Daniel Vetter,
dri-devel, nouveau, linux-kernel, linux-hardening
On Thu, Sep 14, 2023 at 10:17:08PM +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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
The "- 1" use in the original code is strong evidence for this being a
sane conversion. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/nouveau/pm: refactor deprecated strncpy
2023-09-15 4:59 ` Kees Cook
@ 2023-09-15 17:32 ` Lyude Paul
0 siblings, 0 replies; 4+ messages in thread
From: Lyude Paul @ 2023-09-15 17:32 UTC (permalink / raw)
To: Kees Cook, Justin Stitt
Cc: Ben Skeggs, Karol Herbst, David Airlie, Daniel Vetter, dri-devel,
nouveau, linux-kernel, linux-hardening
Nice catch!
Reviewed-by: Lyude Paul <lyude@redhat.com>
Will push in just a moment
On Thu, 2023-09-14 at 21:59 -0700, Kees Cook wrote:
> On Thu, Sep 14, 2023 at 10:17:08PM +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@vger.kernel.org
> > Signed-off-by: Justin Stitt <justinstitt@google.com>
>
> The "- 1" use in the original code is strong evidence for this being a
> sane conversion. :)
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drm/nouveau/pm: refactor deprecated strncpy
2023-09-14 22:17 [PATCH] drm/nouveau/pm: refactor deprecated strncpy Justin Stitt
2023-09-15 4:59 ` Kees Cook
@ 2023-09-15 17:34 ` Lyude Paul
1 sibling, 0 replies; 4+ messages in thread
From: Lyude Paul @ 2023-09-15 17:34 UTC (permalink / raw)
To: Justin Stitt, Ben Skeggs, Karol Herbst, David Airlie,
Daniel Vetter
Cc: dri-devel, nouveau, linux-kernel, linux-hardening
...oops, responded to the wrong email :P
Reviewed-by: Lyude Paul <lyude@redhat.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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.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@google.com>
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
^ permalink raw reply [flat|nested] 4+ messages in thread
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2023-09-14 22:17 [PATCH] drm/nouveau/pm: refactor deprecated strncpy Justin Stitt
2023-09-15 4:59 ` Kees Cook
2023-09-15 17:32 ` Lyude Paul
2023-09-15 17:34 ` Lyude Paul
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