877e91191c
Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
security mitigation that ensures the target of an indirect function call
matches the expected type of the call and trapping if they do not match
exactly. The warning -Wincompatible-function-pointer-types-strict aims
to catch these issues at compile time, which reveals:
drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
598 | leds->led[reg]->cdev.brightness_set_blocking =
| ^
599 | mt6323_wled_set_brightness;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
600 | leds->led[reg]->cdev.brightness_get =
| ^
601 | mt6323_get_wled_brightness;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
2 errors generated.
While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
no warning from -Wincompatible-function-pointer-types) and the callers
of these callbacks use/pass the values as 'unsigned int', the mismatch
between the prototype and the called function will trip kCFI at runtime.
Change the types in the implementations to match the prototypes, clearing
up the warning and avoiding kCFI failures.
Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230622-mt6323-wled-wincompatible-function-pointer-types-strict-v1-1-6ad256f220e8@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.