linux-kernel - drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c:1014:51: warning: 'DCEC' directive output may be truncated writing 4 bytes into a region of size between 0 and 53

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Message-ID: <202412291544.dM7D6yQz-lkp@intel.com>
Date: Sun, 29 Dec 2024 15:24:58 +0800
From: kernel test robot <lkp@...el.com>
To: Hans Verkuil <hverkuil@...all.nl>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org
Subject: drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c:1014:51:
 warning: 'DCEC' directive output may be truncated writing 4 bytes into a
 region of size between 0 and 53

Hi Hans,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   059dd502b263d8a4e2a84809cf1068d6a3905e6f
commit: 056f2821b631df2b94d3b017fd1e1eef918ed98d media: cec: extron-da-hd-4k-plus: add the Extron DA HD 4K Plus CEC driver
date:   4 months ago
config: sparc-randconfig-001-20241212 (https://download.01.org/0day-ci/archive/20241229/202412291544.dM7D6yQz-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 12.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241229/202412291544.dM7D6yQz-lkp@intel.com/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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412291544.dM7D6yQz-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c: In function 'extron_cec_adap_transmit':
>> drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c:1014:51: warning: 'DCEC' directive output may be truncated writing 4 bytes into a region of size between 0 and 53 [-Wformat-truncation=]
    1014 |         snprintf(cmd, sizeof(cmd), "W%c%u*%u*%u*%sDCEC",
         |                                                   ^~~~
   drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c:1014:9: note: 'snprintf' output between 13 and 72 bytes into a destination of size 61
    1014 |         snprintf(cmd, sizeof(cmd), "W%c%u*%u*%u*%sDCEC",
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    1015 |                  port->direction, port->port.port,
         |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    1016 |                  cec_msg_initiator(msg), cec_msg_destination(msg), buf);
         |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/DCEC +1014 drivers/media/cec/usb/extron-da-hd-4k-plus/extron-da-hd-4k-plus.c

  1000	
  1001	static int extron_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
  1002					    u32 signal_free_time, struct cec_msg *msg)
  1003	{
  1004		struct extron_port *port = cec_get_drvdata(adap);
  1005		char buf[CEC_MAX_MSG_SIZE * 3 + 1];
  1006		char cmd[CEC_MAX_MSG_SIZE * 3 + 13];
  1007		unsigned int i;
  1008	
  1009		if (port->disconnected)
  1010			return -ENODEV;
  1011		buf[0] = 0;
  1012		for (i = 0; i < msg->len - 1; i++)
  1013			sprintf(buf + i * 3, "%%%02X", msg->msg[i + 1]);
> 1014		snprintf(cmd, sizeof(cmd), "W%c%u*%u*%u*%sDCEC",
  1015			 port->direction, port->port.port,
  1016			 cec_msg_initiator(msg), cec_msg_destination(msg), buf);
  1017		return extron_send_and_wait(port->extron, port, cmd, NULL);
  1018	}
  1019	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki