linux/drivers/leds/leds-spi-byte.c
Azeem Shaikh bf4a35e920 leds: Replace all non-returning strlcpy with strscpy
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230523021451.2406362-1-azeemshaikh38@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>
2023-05-25 12:31:55 +01:00

155 lines
4.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Christian Mauderer <oss@c-mauderer.de>
/*
* The driver supports controllers with a very simple SPI protocol:
* - one LED is controlled by a single byte on MOSI
* - the value of the byte gives the brightness between two values (lowest to
* highest)
* - no return value is necessary (no MISO signal)
*
* The value for minimum and maximum brightness depends on the device
* (compatible string).
*
* Supported devices:
* - "ubnt,acb-spi-led": Microcontroller (SONiX 8F26E611LA) based device used
* for example in Ubiquiti airCube ISP. Reverse engineered protocol for this
* controller:
* * Higher two bits set a mode. Lower six bits are a parameter.
* * Mode: 00 -> set brightness between 0x00 (min) and 0x3F (max)
* * Mode: 01 -> pulsing pattern (min -> max -> min) with an interval. From
* some tests, the period is about (50ms + 102ms * parameter). There is a
* slightly different pattern starting from 0x10 (longer gap between the
* pulses) but the time still follows that calculation.
* * Mode: 10 -> same as 01 but with only a ramp from min to max. Again a
* slight jump in the pattern at 0x10.
* * Mode: 11 -> blinking (off -> 25% -> off -> 25% -> ...) with a period of
* (105ms * parameter)
* NOTE: This driver currently only supports mode 00.
*/
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
#include <linux/mutex.h>
#include <uapi/linux/uleds.h>
struct spi_byte_chipdef {
/* SPI byte that will be send to switch the LED off */
u8 off_value;
/* SPI byte that will be send to switch the LED to maximum brightness */
u8 max_value;
};
struct spi_byte_led {
struct led_classdev ldev;
struct spi_device *spi;
char name[LED_MAX_NAME_SIZE];
struct mutex mutex;
const struct spi_byte_chipdef *cdef;
};
static const struct spi_byte_chipdef ubnt_acb_spi_led_cdef = {
.off_value = 0x0,
.max_value = 0x3F,
};
static const struct of_device_id spi_byte_dt_ids[] = {
{ .compatible = "ubnt,acb-spi-led", .data = &ubnt_acb_spi_led_cdef },
{},
};
MODULE_DEVICE_TABLE(of, spi_byte_dt_ids);
static int spi_byte_brightness_set_blocking(struct led_classdev *dev,
enum led_brightness brightness)
{
struct spi_byte_led *led = container_of(dev, struct spi_byte_led, ldev);
u8 value;
int ret;
value = (u8) brightness + led->cdef->off_value;
mutex_lock(&led->mutex);
ret = spi_write(led->spi, &value, sizeof(value));
mutex_unlock(&led->mutex);
return ret;
}
static int spi_byte_probe(struct spi_device *spi)
{
struct device_node *child;
struct device *dev = &spi->dev;
struct spi_byte_led *led;
const char *name = "leds-spi-byte::";
const char *state;
int ret;
if (of_get_available_child_count(dev_of_node(dev)) != 1) {
dev_err(dev, "Device must have exactly one LED sub-node.");
return -EINVAL;
}
child = of_get_next_available_child(dev_of_node(dev), NULL);
led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
if (!led)
return -ENOMEM;
of_property_read_string(child, "label", &name);
strscpy(led->name, name, sizeof(led->name));
led->spi = spi;
mutex_init(&led->mutex);
led->cdef = device_get_match_data(dev);
led->ldev.name = led->name;
led->ldev.brightness = LED_OFF;
led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;
led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;
state = of_get_property(child, "default-state", NULL);
if (state) {
if (!strcmp(state, "on")) {
led->ldev.brightness = led->ldev.max_brightness;
} else if (strcmp(state, "off")) {
/* all other cases except "off" */
dev_err(dev, "default-state can only be 'on' or 'off'");
return -EINVAL;
}
}
spi_byte_brightness_set_blocking(&led->ldev,
led->ldev.brightness);
ret = devm_led_classdev_register(&spi->dev, &led->ldev);
if (ret) {
mutex_destroy(&led->mutex);
return ret;
}
spi_set_drvdata(spi, led);
return 0;
}
static void spi_byte_remove(struct spi_device *spi)
{
struct spi_byte_led *led = spi_get_drvdata(spi);
mutex_destroy(&led->mutex);
}
static struct spi_driver spi_byte_driver = {
.probe = spi_byte_probe,
.remove = spi_byte_remove,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = spi_byte_dt_ids,
},
};
module_spi_driver(spi_byte_driver);
MODULE_AUTHOR("Christian Mauderer <oss@c-mauderer.de>");
MODULE_DESCRIPTION("single byte SPI LED driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:leds-spi-byte");