Given the following code containing errors, provide Common Weakness Enumeration (CWE) identifiers and corresponding messages in JSON format. Each identified weakness should have a unique entry in the JSON array.
    Code: static int do_i2c_crc(struct cmd_tbl *cmdtp, int flag, int argc,
		      char *const argv[])
{
	uint	chip;
	ulong	addr;
	int	alen;
	int	count;
	uchar	byte;
	ulong	crc;
	ulong	err;
	int ret = 0;
#if CONFIG_IS_ENABLED(DM_I2C)
	struct udevice *dev;
#endif

	if (argc < 4)
		return CMD_RET_USAGE;

	/*
	 * Chip is always specified.
	 */
	chip = hextoul(argv[1], NULL);

	/*
	 * Address is always specified.
	 */
	addr = hextoul(argv[2], NULL);
	alen = get_alen(argv[2], DEFAULT_ADDR_LEN);
	if (alen > 3)
		return CMD_RET_USAGE;

#if CONFIG_IS_ENABLED(DM_I2C)
	ret = i2c_get_cur_bus_chip(chip, &dev);
	if (!ret && alen != -1)
		ret = i2c_set_chip_offset_len(dev, alen);
	if (ret)
		return i2c_report_err(ret, I2C_ERR_READ);
#endif
	/*
	 * Count is always specified
	 */
	count = hextoul(argv[3], NULL);

	printf ("CRC32 for %08lx ... %08lx ==> ", addr, addr + count - 1);
	/*
	 * CRC a byte at a time.  This is going to be slooow, but hey, the
	 * memories are small and slow too so hopefully nobody notices.
	 */
	crc = 0;
	err = 0;
	while (count-- > 0) {
#if CONFIG_IS_ENABLED(DM_I2C)
		ret = dm_i2c_read(dev, addr, &byte, 1);
#else
		ret = i2c_read(chip, addr, alen, &byte, 1);
#endif
		if (ret)
			err++;
		crc = crc32(crc, &byte, 1);
		addr++;
	}
	if (err > 0)
		i2c_report_err(ret, I2C_ERR_READ);
	else
		printf ("%08lx\n", crc);

	return 0;
} ; Sample JSON Format Confermily Expected output: "examples" => "cwe": "xxx"; "message": "xxx"
    
 'cwe': ['CWE-787'], 'message': 'i2c: fix stack buffer overflow vulnerability in i2c md command

When running "i2c md 0 0 80000100", the function do_i2c_md parses the
length into an unsigned int variable named length. The value is then
moved to a signed variable:

    int nbytes = length;
    #define DISP_LINE_LEN 16
    int linebytes = (nbytes > DISP_LINE_LEN) ? DISP_LINE_LEN : nbytes;
    ret = dm_i2c_read(dev, addr, linebuf, linebytes);

On systems where integers are 32 bits wide, 0x80000100 is a negative
value to "nbytes > DISP_LINE_LEN" is false and linebytes gets assigned
0x80000100 instead of 16.

The consequence is that the function which reads from the i2c device
(dm_i2c_read or i2c_read) is called with a 16-byte stack buffer to fill
but with a size parameter which is too large. In some cases, this could
trigger a crash. But with some i2c drivers, such as drivers/i2c/nx_i2c.c
(used with "nexell,s5pxx18-i2c" bus), the size is actually truncated to
a 16-bit integer. This is because function i2c_transfer expects an
unsigned short length. In such a case, an attacker who can control the
response of an i2c device can overwrite the return address of a function
and execute arbitrary code through Return-Oriented Programming.

Fix this issue by using unsigned integers types in do_i2c_md. While at
it, make also alen unsigned, as signed sizes can cause vulnerabilities
when people forgot to check that they can be negative.

Signed-off-by: Nicolas Iooss <nicolas.iooss+uboot@ledger.fr>
Reviewed-by: Heiko Schocher <hs@denx.de>'