linux-stable.git/drivers/gpu/drm/drm_modes.c, branch linux-6.8.y

drm/modes: replace deprecated strncpy with strscpy_pad

2023-12-01T17:51:43+00:00

`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

drm: Fix comment on mode parsing

2023-02-20T13:56:52+00:00

Do not claim that there's a default mode in the video= option parser.
if no option string has been given, the parser does nothing.

Signed-off-by: Thomas Zimmermann 
Reviewed-by: Javier Martinez Canillas 
Link: https://patchwork.freedesktop.org/patch/msgid/20230209135509.7786-12-tzimmermann@suse.de

drm: Include where needed

2023-01-13T12:18:35+00:00

Include  in source files that need it. Some of DRM's
source code gets OF header via drm_crtc_helper.h and ,
which can leed to unnecessary recompilation.

In drm_modes.c, add a comment on the reason for still including
. The header file is required to get KHZ2PICOS(). The
macro is part of the UAPI headers, so it cannot be moved to a less
prominent location.

v2:
	* include  in komeda_drv.c (kernel test robot)

Signed-off-by: Thomas Zimmermann 
Acked-by: Liviu Dudau  # komeda
Acked-by: Maxime Ripard 
Link: https://patchwork.freedesktop.org/patch/msgid/20230111130206.29974-3-tzimmermann@suse.de

drm/modes: Use strscpy() to copy command-line mode name

2022-12-01T10:12:44+00:00

The mode name in struct drm_cmdline_mode can hold 32 characters at most,
which can easily get overrun. Switch to strscpy() to prevent such a
thing.

Reported-by: coverity-bot 
Addresses-Coverity-ID: 1527354 ("Security best practices violations")
Fixes: a7ab155397dd ("drm/modes: Switch to named mode descriptors")
Reviewed-by: Javier Martinez Canillas 
Link: https://lore.kernel.org/r/20221128081938.742410-2-maxime@cerno.tech
Signed-off-by: Maxime Ripard

drm/modes: Introduce more named modes

2022-11-24T11:42:40+00:00

Now that we can easily extend the named modes list, let's add a few more
analog TV modes that were used in the wild, and some unit tests to make
sure it works as intended.

Reviewed-by: Noralf Trønnes 
Tested-by: Mateusz Kwiatkowski 
Acked-in-principle-or-something-like-that-by: Daniel Vetter 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-11-256dad125326@cerno.tech
Signed-off-by: Maxime Ripard

drm/modes: Properly generate a drm_display_mode from a named mode

2022-11-24T11:42:39+00:00

The framework will get the drm_display_mode from the drm_cmdline_mode it
got by parsing the video command line argument by calling
drm_connector_pick_cmdline_mode().

The heavy lifting will then be done by the
drm_mode_create_from_cmdline_mode() function.

In the case of the named modes though, there's no real code to make that
translation and we rely on the drivers to guess which actual display mode
we meant.

Let's modify drm_mode_create_from_cmdline_mode() to properly generate the
drm_display_mode we mean when passing a named mode.

Reviewed-by: Noralf Trønnes 
Tested-by: Mateusz Kwiatkowski 
Acked-in-principle-or-something-like-that-by: Daniel Vetter 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-9-256dad125326@cerno.tech
Signed-off-by: Maxime Ripard

drm/modes: Introduce the tv_mode property as a command-line option

2022-11-24T11:42:39+00:00

Our new tv mode option allows to specify the TV mode from a property.
However, it can still be useful, for example to avoid any boot time
artifact, to set that property directly from the kernel command line.

Let's add some code to allow it, and some unit tests to exercise that code.

Reviewed-by: Noralf Trønnes 
Tested-by: Mateusz Kwiatkowski 
Acked-in-principle-or-something-like-that-by: Daniel Vetter 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-8-256dad125326@cerno.tech
Signed-off-by: Maxime Ripard

drm/modes: Add a function to generate analog display modes

2022-11-24T11:42:39+00:00

Multiple drivers (meson, vc4, sun4i) define analog TV 525-lines and
625-lines modes in their drivers.

Since those modes are fairly standard, and that we'll need to use them
in more places in the future, it makes sense to move their definition
into the core framework.

However, analog display usually have fairly loose timings requirements,
the only discrete parameters being the total number of lines and pixel
clock frequency. Thus, we created a function that will create a display
mode from the standard, the pixel frequency and the active area.

Tested-by: Mateusz Kwiatkowski 
Acked-in-principle-or-something-like-that-by: Daniel Vetter 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-6-256dad125326@cerno.tech
Signed-off-by: Maxime Ripard

drm/connector: Add pixel clock to cmdline mode

2022-11-15T09:10:24+00:00

We'll need to get the pixel clock to generate proper display modes for
all the current named modes. Let's add it to struct drm_cmdline_mode and
fill it when parsing the named mode.

Reviewed-by: Noralf Trønnes 
Tested-by: Mateusz Kwiatkowski 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v9-12-24b168e5bcd5@cerno.tech
Signed-off-by: Maxime Ripard

drm/modes: Fill drm_cmdline mode from named modes

2022-11-15T09:10:14+00:00

The current code to deal with named modes will only set the mode name, and
then it's up to drivers to try to match that name to whatever mode or
configuration they see fit.

The plan is to remove that need and move the named mode handling out of
drivers and into the core, and only rely on modes and properties. Let's
start by properly filling drm_cmdline_mode from a named mode.

Reviewed-by: Noralf Trønnes 
Tested-by: Mateusz Kwiatkowski 
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v9-11-24b168e5bcd5@cerno.tech
Signed-off-by: Maxime Ripard