[Coverity CID :197534]Memory - corruptions in /subsys/logging/log_backend_rtt.c

[aasthagr]

Static code scan issues seen in File: /subsys/logging/log_backend_rtt.c
Category: Memory - corruptions
Function: line_out_drop_mode
Component: Other
CID: 197534
Please fix or provide comments to square it off in coverity in the link: https://scan9.coverity.com/reports.htm#v32951/p12996

[nashif]

** CID 197534:  Memory - corruptions  (OVERRUN)
/subsys/logging/log_backend_rtt.c: 114 in line_out_drop_mode()


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*** CID 197534:  Memory - corruptions  (OVERRUN)
/subsys/logging/log_backend_rtt.c: 114 in line_out_drop_mode()
108     
109     static int line_out_drop_mode(void)
110     {
111     	*line_pos = '\r';
112     
113     	if (drop_cnt > 0 && !drop_warn) {
>>>     CID 197534:  Memory - corruptions  (OVERRUN)
>>>     Overrunning buffer pointed to by "line_buf + 23UL" of 23 bytes 
>>> by passing it to a function which accesses it at byte offset 23. 
>>> [Note: The source code implementation of the function has been 
>>> overridden by a builtin model.]
114     		memmove(line_buf + DROP_MSG_LEN, line_buf,
115     			line_pos - line_buf);
116     		(void)memcpy(line_buf, drop_msg, DROP_MSG_LEN);
117     		line_pos += DROP_MSG_LEN;
118     		drop_warn = 1;
119     	}