From 513348f4e4d1d507b683d85daec8a14621e374b8 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Mon, 16 Oct 2023 22:38:20 +0000 Subject: [PATCH] drm/modes: replace deprecated strncpy with strscpy_pad `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 Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20231016-strncpy-drivers-gpu-drm-drm_modes-c-v2-1-d0b60686e1c6@google.com Signed-off-by: Kees Cook --- drivers/gpu/drm/drm_modes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c index ac9a406250c..893f52ee492 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