When not all LED channels of the device are configured in OF, the array size of pdata->led_config is smaller than the max number of channels on the device. Subsequent accesses to pdata->led_config[i] are going beyond the bounds of the allocated array. The check on the configured led_current is also invalid, resulting in erroneous test results for this function.
There is a potential for LED overcurrent conditions since the test current will be set to values from these out-of-bound regions. For the test, the PWM is set to 100%, although for a short amount of time.
Instead of iterating over all the physical channels of the device, loop over the available LED configurations and use led->chan_nr to access the correct i2c registers. Keep the zero-check for the LED current as existing configurations might depend on this to disable a channel.
Cc: stable@vger.kernel.org Cc: dmurphy@ti.com Cc: milo.kim@ti.com Reported-by: Arne Staessen a.staessen@televic.com Signed-off-by: Maarten Zanders maarten.zanders@mind.be --- drivers/leds/leds-lp5523.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c index b1590cb4a188..f3782759c8d8 100644 --- a/drivers/leds/leds-lp5523.c +++ b/drivers/leds/leds-lp5523.c @@ -581,8 +581,8 @@ static ssize_t lp5523_selftest(struct device *dev, struct lp55xx_led *led = i2c_get_clientdata(to_i2c_client(dev)); struct lp55xx_chip *chip = led->chip; struct lp55xx_platform_data *pdata = chip->pdata; - int i, ret, pos = 0; - u8 status, adc, vdd; + int ret, pos = 0; + u8 status, adc, vdd, i;
mutex_lock(&chip->lock);
@@ -612,20 +612,20 @@ static ssize_t lp5523_selftest(struct device *dev,
vdd--; /* There may be some fluctuation in measurement */
- for (i = 0; i < LP5523_MAX_LEDS; i++) { - /* Skip non-existing channels */ + for (i = 0; i < pdata->num_channels; i++) { + /* Skip disabled channels */ if (pdata->led_config[i].led_current == 0) continue;
/* Set default current */ - lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + i, + lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + led->chan_nr, pdata->led_config[i].led_current);
- lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + i, 0xff); + lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr, 0xff); /* let current stabilize 2 - 4ms before measurements start */ usleep_range(2000, 4000); lp55xx_write(chip, LP5523_REG_LED_TEST_CTRL, - LP5523_EN_LEDTEST | i); + LP5523_EN_LEDTEST | led->chan_nr); /* ADC conversion time is 2.7 ms typically */ usleep_range(3000, 6000); ret = lp55xx_read(chip, LP5523_REG_STATUS, &status); @@ -640,12 +640,12 @@ static ssize_t lp5523_selftest(struct device *dev, goto fail;
if (adc >= vdd || adc < LP5523_ADC_SHORTCIRC_LIM) - pos += sprintf(buf + pos, "LED %d FAIL\n", i); + pos += sprintf(buf + pos, "LED %d FAIL\n", led->chan_nr);
- lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + i, 0x00); + lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr, 0x00);
/* Restore current */ - lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + i, + lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + led->chan_nr, led->led_current); led++; }