| Message ID | 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-v1-1-3aeae46c032f@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/nouveau/core: refactor deprecated strncpy | expand |
On Thu, Sep 14, 2023 at 09:40:49PM +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. > > There is likely no bug in the current implementation due to the safeguard: > | cname[sizeof(cname) - 1] = '\0'; > ... however we can provide simpler and easier to understand code using > the newer (and recommended) `strscpy` api. > > 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/core/firmware.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > index 91fb494d4009..374212da9e95 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > +++ b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > @@ -79,8 +79,7 @@ nvkm_firmware_get(const struct nvkm_subdev *subdev, const char *fwname, int ver, > int i; > > /* Convert device name to lowercase */ > - strncpy(cname, device->chip->name, sizeof(cname)); > - cname[sizeof(cname) - 1] = '\0'; > + strscpy(cname, device->chip->name, sizeof(cname)); > i = strlen(cname); > while (i) { > --i; Yup, consumed by strlen() and snprintf(). Looks like a standard conversion. :) Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > > --- > base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec > change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-791223838b72 > > Best regards, > -- > Justin Stitt <justinstitt@google.com> >
Eek, I didn't realize how many instances of this we had. Thanks for doing this :) Reviewed-by: Lyude Paul <lyude@redhat.com> On Thu, 2023-09-14 at 21:40 +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. > > There is likely no bug in the current implementation due to the safeguard: > > cname[sizeof(cname) - 1] = '\0'; > ... however we can provide simpler and easier to understand code using > the newer (and recommended) `strscpy` api. > > 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/core/firmware.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > index 91fb494d4009..374212da9e95 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > +++ b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c > @@ -79,8 +79,7 @@ nvkm_firmware_get(const struct nvkm_subdev *subdev, const char *fwname, int ver, > int i; > > /* Convert device name to lowercase */ > - strncpy(cname, device->chip->name, sizeof(cname)); > - cname[sizeof(cname) - 1] = '\0'; > + strscpy(cname, device->chip->name, sizeof(cname)); > i = strlen(cname); > while (i) { > --i; > > --- > base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec > change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-791223838b72 > > Best regards, > -- > Justin Stitt <justinstitt@google.com> >
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c index 91fb494d4009..374212da9e95 100644 --- a/drivers/gpu/drm/nouveau/nvkm/core/firmware.c +++ b/drivers/gpu/drm/nouveau/nvkm/core/firmware.c @@ -79,8 +79,7 @@ nvkm_firmware_get(const struct nvkm_subdev *subdev, const char *fwname, int ver, int i; /* Convert device name to lowercase */ - strncpy(cname, device->chip->name, sizeof(cname)); - cname[sizeof(cname) - 1] = '\0'; + strscpy(cname, device->chip->name, sizeof(cname)); i = strlen(cname); while (i) { --i;
`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. There is likely no bug in the current implementation due to the safeguard: | cname[sizeof(cname) - 1] = '\0'; ... however we can provide simpler and easier to understand code using the newer (and recommended) `strscpy` api. 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/core/firmware.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvkm-core-firmware-c-791223838b72 Best regards, -- Justin Stitt <justinstitt@google.com>