Re: [PATCH v1 1/1] leds: pca955x: Avoid potential overflow when filling default_label
From: kernel test robot
Date: Fri Apr 04 2025 - 14:59:08 EST
Hi Andy,
kernel test robot noticed the following build warnings:
[auto build test WARNING on v6.14]
[cannot apply to lee-leds/for-leds-next linus/master next-20250404]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Andy-Shevchenko/leds-pca955x-Avoid-potential-overflow-when-filling-default_label/20250405-003054
base: v6.14
patch link: https://lore.kernel.org/r/20250404162849.3650361-1-andriy.shevchenko%40linux.intel.com
patch subject: [PATCH v1 1/1] leds: pca955x: Avoid potential overflow when filling default_label
config: powerpc-randconfig-003-20250405 (https://download.01.org/0day-ci/archive/20250405/202504050256.SYq06TxB-lkp@xxxxxxxxx/config)
compiler: powerpc-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250405/202504050256.SYq06TxB-lkp@xxxxxxxxx/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202504050256.SYq06TxB-lkp@xxxxxxxxx/
All warnings (new ones prefixed by >>):
drivers/leds/leds-pca955x.c: In function 'pca955x_probe':
>> drivers/leds/leds-pca955x.c:554:53: warning: '%u' directive output may be truncated writing between 1 and 10 bytes into a region of size 8 [-Wformat-truncation=]
snprintf(default_label, sizeof(default_label), "%u", i);
^~
drivers/leds/leds-pca955x.c:554:52: note: directive argument in the range [0, 4294967294]
snprintf(default_label, sizeof(default_label), "%u", i);
^~~~
drivers/leds/leds-pca955x.c:554:5: note: 'snprintf' output between 2 and 11 bytes into a destination of size 8
snprintf(default_label, sizeof(default_label), "%u", i);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vim +554 drivers/leds/leds-pca955x.c
449
450 static int pca955x_probe(struct i2c_client *client)
451 {
452 struct pca955x *pca955x;
453 struct pca955x_led *pca955x_led;
454 const struct pca955x_chipdef *chip;
455 struct led_classdev *led;
456 struct led_init_data init_data;
457 struct i2c_adapter *adapter;
458 struct pca955x_platform_data *pdata;
459 bool set_default_label = false;
460 bool keep_pwm = false;
461 char default_label[8];
462 unsigned int i;
463 int err;
464
465 chip = i2c_get_match_data(client);
466 if (!chip)
467 return dev_err_probe(&client->dev, -ENODEV, "unknown chip\n");
468
469 adapter = client->adapter;
470 pdata = dev_get_platdata(&client->dev);
471 if (!pdata) {
472 pdata = pca955x_get_pdata(client, chip);
473 if (IS_ERR(pdata))
474 return PTR_ERR(pdata);
475 }
476
477 /* Make sure the slave address / chip type combo given is possible */
478 if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
479 chip->slv_addr) {
480 dev_err(&client->dev, "invalid slave address %02x\n",
481 client->addr);
482 return -ENODEV;
483 }
484
485 dev_info(&client->dev, "Using %s %u-bit LED driver at slave address 0x%02x\n",
486 client->name, chip->bits, client->addr);
487
488 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
489 return -EIO;
490
491 if (pdata->num_leds != chip->bits) {
492 dev_err(&client->dev,
493 "board info claims %d LEDs on a %u-bit chip\n",
494 pdata->num_leds, chip->bits);
495 return -ENODEV;
496 }
497
498 pca955x = devm_kzalloc(&client->dev, sizeof(*pca955x), GFP_KERNEL);
499 if (!pca955x)
500 return -ENOMEM;
501
502 pca955x->leds = devm_kcalloc(&client->dev, chip->bits,
503 sizeof(*pca955x_led), GFP_KERNEL);
504 if (!pca955x->leds)
505 return -ENOMEM;
506
507 i2c_set_clientdata(client, pca955x);
508
509 mutex_init(&pca955x->lock);
510 pca955x->client = client;
511 pca955x->chipdef = chip;
512
513 init_data.devname_mandatory = false;
514 init_data.devicename = "pca955x";
515
516 for (i = 0; i < chip->bits; i++) {
517 pca955x_led = &pca955x->leds[i];
518 pca955x_led->led_num = i;
519 pca955x_led->pca955x = pca955x;
520 pca955x_led->type = pdata->leds[i].type;
521
522 switch (pca955x_led->type) {
523 case PCA955X_TYPE_NONE:
524 case PCA955X_TYPE_GPIO:
525 break;
526 case PCA955X_TYPE_LED:
527 led = &pca955x_led->led_cdev;
528 led->brightness_set_blocking = pca955x_led_set;
529 led->brightness_get = pca955x_led_get;
530
531 if (pdata->leds[i].default_state == LEDS_DEFSTATE_OFF) {
532 err = pca955x_led_set(led, LED_OFF);
533 if (err)
534 return err;
535 } else if (pdata->leds[i].default_state == LEDS_DEFSTATE_ON) {
536 err = pca955x_led_set(led, LED_FULL);
537 if (err)
538 return err;
539 }
540
541 init_data.fwnode = pdata->leds[i].fwnode;
542
543 if (is_of_node(init_data.fwnode)) {
544 if (to_of_node(init_data.fwnode)->name[0] ==
545 '\0')
546 set_default_label = true;
547 else
548 set_default_label = false;
549 } else {
550 set_default_label = true;
551 }
552
553 if (set_default_label) {
> 554 snprintf(default_label, sizeof(default_label), "%u", i);
555 init_data.default_label = default_label;
556 } else {
557 init_data.default_label = NULL;
558 }
559
560 err = devm_led_classdev_register_ext(&client->dev, led,
561 &init_data);
562 if (err)
563 return err;
564
565 set_bit(i, &pca955x->active_pins);
566
567 /*
568 * For default-state == "keep", let the core update the
569 * brightness from the hardware, then check the
570 * brightness to see if it's using PWM1. If so, PWM1
571 * should not be written below.
572 */
573 if (pdata->leds[i].default_state == LEDS_DEFSTATE_KEEP) {
574 if (led->brightness != LED_FULL &&
575 led->brightness != LED_OFF &&
576 led->brightness != LED_HALF)
577 keep_pwm = true;
578 }
579 }
580 }
581
582 /* PWM0 is used for half brightness or 50% duty cycle */
583 err = pca955x_write_pwm(client, 0, 255 - LED_HALF);
584 if (err)
585 return err;
586
587 if (!keep_pwm) {
588 /* PWM1 is used for variable brightness, default to OFF */
589 err = pca955x_write_pwm(client, 1, 0);
590 if (err)
591 return err;
592 }
593
594 /* Set to fast frequency so we do not see flashing */
595 err = pca955x_write_psc(client, 0, 0);
596 if (err)
597 return err;
598 err = pca955x_write_psc(client, 1, 0);
599 if (err)
600 return err;
601
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki