| Message ID | 20230914-strncpy-drivers-gpu-drm-drm_modes-c-v1-1-079b532553a3@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/modes: refactor deprecated strncpy | expand |
On Thu, Sep 14, 2023 at 06:08:44PM +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 and doesn't incur the > performance loss of unnecessarily NUL-padding. How did you decide it didn't need %NUL padding? I suspect it should have it, as I see what looks like 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); Can you send a v2 using strscpy_pad() instead? Thanks! -Kees
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c index ac9a406250c5..c702a8b866cf 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(out->name, in->name, DRM_DISPLAY_MODE_LEN); } /** @@ -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(out->name, in->name, DRM_DISPLAY_MODE_LEN); /* 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]. 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 and doesn't incur the performance loss of 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 Cc: Xu Panda <xu.panda@zte.com.cn> Signed-off-by: Justin Stitt <justinstitt@google.com> --- This patch is basically a resend of [1] by Xu but rebased onto mainline. This patch is also similar to: commit 0f9aa074c92dd ("drm/modes: Use strscpy() to copy command-line mode name") [1]: https://lore.kernel.org/all/202212051935289159302@zte.com.cn/ --- drivers/gpu/drm/drm_modes.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec change-id: 20230914-strncpy-drivers-gpu-drm-drm_modes-c-a35d782cad01 Best regards, -- Justin Stitt <justinstitt@google.com>