ocp: telemetry parser buffer overflow for events exceeding 32 dwords

[NateThornton]

Buffer overflow encountered when parsing OCP telemetry data

void print_formatted_var_size_str(const char *msg, const __u8 *pdata, size_t data_size, FILE *fp)
{
	char description_str[256] = "";
	char temp_buffer[3] = { 0 };

	for (size_t i = 0; i < data_size; ++i) {
		sprintf(temp_buffer, "%02X", pdata[i]);
		strcat(description_str, temp_buffer);
	}

	if (fp)
		fprintf(fp, "%s: %s\n", msg, description_str);
	else
		printf("%s: %s\n", msg, description_str);
}

The fixed 256-byte description_str will overflow for any reasonably sized data_size >= 128.

Max data_size is for OCP VU Event Data is 0xFF Dwords, so the buffer should be at least 1020 bytes + 1 for null. 1024 seems like a nice number for OCP.

But this method was added to utils.c in e9c2e8f and any caller could overflow this buffer. While making it larger for the current ocp-telemetry-decode.c use cases one should also prevent buffer overflows for all users.