Optimization-unstable code

Posted Dec 5, 2013 13:42 UTC (Thu) by HelloWorld (guest, #56129)
In reply to: Optimization-unstable code by Felix.Braun
Parent article: Optimization-unstable code

That makes no sense. Why would there be any relationship between the buffer's bounds and len's address? You do have a point though: the check quoted in the LWN article is insufficient, and in fact, the check in the paper is different:

char *buf = ...;
char *buf_end = ...;
unsigned int len = ...;
if (buf + len >= buf_end)
  return;   /* len too large */
if (buf + len < buf)
  return;   /* overflow, buf+len wrapped around */
/* write to buf[0..len-1] */