| Message ID | 20231016-strncpy-drivers-gpu-drm-drm_modes-c-v2-1-d0b60686e1c6@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/modes: replace deprecated strncpy with strscpy_pad | expand |
On Mon, Oct 16, 2023 at 10:38:20PM +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We should NUL-pad as there are full struct copies happening in places: > | struct drm_mode_modeinfo umode; > | > | ... > | struct drm_property_blob *blob; > | > | drm_mode_convert_to_umode(&umode, mode); > | blob = drm_property_create_blob(crtc->dev, > | sizeof(umode), &umode); > > A suitable replacement is `strscpy_pad` due to the fact that it > guarantees both NUL-termination and NUL-padding on the destination > buffer. > > Additionally, replace size macro `DRM_DISPLAY_MODE_LEN` with sizeof() to > more directly tie the maximum buffer size to the destination buffer: > | struct drm_display_mode { > | ... > | char name[DRM_DISPLAY_MODE_LEN]; > > 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@vger.kernel.org > Cc: Xu Panda <xu.panda@zte.com.cn> > Signed-off-by: Justin Stitt <justinstitt@google.com> Thanks for the respin; this looks good to me. Reviewed-by: Kees Cook <keescook@chromium.org>
On Mon, 16 Oct 2023 22:38:20 +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We should NUL-pad as there are full struct copies happening in places: > | struct drm_mode_modeinfo umode; > | > | ... > | struct drm_property_blob *blob; > | > | drm_mode_convert_to_umode(&umode, mode); > | blob = drm_property_create_blob(crtc->dev, > | sizeof(umode), &umode); > > [...] Applied to for-next/hardening, thanks! [1/1] drm/modes: replace deprecated strncpy with strscpy_pad https://git.kernel.org/kees/c/d8d273c595db Take care,
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c index ac9a406250c5..893f52ee4926 100644 --- a/drivers/gpu/drm/drm_modes.c +++ b/drivers/gpu/drm/drm_modes.c @@ -2617,8 +2617,7 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out, break; } - strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN); - out->name[DRM_DISPLAY_MODE_LEN-1] = 0; + strscpy_pad(out->name, in->name, sizeof(out->name)); } /** @@ -2659,8 +2658,7 @@ int drm_mode_convert_umode(struct drm_device *dev, * useful for the kernel->userspace direction anyway. */ out->type = in->type & DRM_MODE_TYPE_ALL; - strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN); - out->name[DRM_DISPLAY_MODE_LEN-1] = 0; + strscpy_pad(out->name, in->name, sizeof(out->name)); /* Clearing picture aspect ratio bits from out flags, * as the aspect-ratio information is not stored in
`strncpy` is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We should NUL-pad as there are full struct copies happening in places: | struct drm_mode_modeinfo umode; | | ... | struct drm_property_blob *blob; | | drm_mode_convert_to_umode(&umode, mode); | blob = drm_property_create_blob(crtc->dev, | sizeof(umode), &umode); A suitable replacement is `strscpy_pad` due to the fact that it guarantees both NUL-termination and NUL-padding on the destination buffer. Additionally, replace size macro `DRM_DISPLAY_MODE_LEN` with sizeof() to more directly tie the maximum buffer size to the destination buffer: | struct drm_display_mode { | ... | char name[DRM_DISPLAY_MODE_LEN]; 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@vger.kernel.org Cc: Xu Panda <xu.panda@zte.com.cn> Signed-off-by: Justin Stitt <justinstitt@google.com> --- Changes in v2: - use strscpy_pad (thanks Kees) - rebase onto mainline - Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-gpu-drm-drm_modes-c-v1-1-079b532553a3@google.com --- Note: build-tested only. --- drivers/gpu/drm/drm_modes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- base-commit: 58720809f52779dc0f08e53e54b014209d13eebb change-id: 20230914-strncpy-drivers-gpu-drm-drm_modes-c-a35d782cad01 Best regards, -- Justin Stitt <justinstitt@google.com>