This is a note to let you know that I've just added the patch titled
drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-fsl-dcu-fix-return-type-of-fsl_dcu_drm_connector.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e1b745091bd2d1d82ffdc057fe82ac58c10603f3
Author: Nathan Chancellor <nathan@xxxxxxxxxx>
Date: Wed Nov 2 08:42:15 2022 -0700
drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
[ Upstream commit 96d845a67b7e406cfed7880a724c8ca6121e022e ]
With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed. A
proposed warning in clang aims to catch these at compile time, which
reveals:
drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c:74:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_connector *, struct drm_display_mode *)' with an expression of type 'int (struct drm_connector *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict]
.mode_valid = fsl_dcu_drm_connector_mode_valid,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
->mode_valid() in 'struct drm_connector_helper_funcs' expects a return
type of 'enum drm_mode_status', not 'int'. Adjust the return type of
fsl_dcu_drm_connector_mode_valid() to match the prototype's to resolve
the warning and CFI failure.
Link: https://github.com/ClangBuiltLinux/linux/issues/1750
Reported-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221102154215.78059-1-nathan@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
index e1dd75b18118..5993d6ac85e6 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
@@ -90,8 +90,9 @@ static int fsl_dcu_drm_connector_get_modes(struct drm_connector *connector)
return num_modes;
}
-static int fsl_dcu_drm_connector_mode_valid(struct drm_connector *connector,
- struct drm_display_mode *mode)
+static enum drm_mode_status
+fsl_dcu_drm_connector_mode_valid(struct drm_connector *connector,
+ struct drm_display_mode *mode)
{
if (mode->hdisplay & 0xf)
return MODE_ERROR;
