https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67536
Bug ID: 67536 Summary: unix.c sanitizer detects null pointer passed to memcpy Product: gcc Version: 5.2.0 Status: UNCONFIRMED Severity: minor Priority: P3 Component: libfortran Assignee: unassigned at gcc dot gnu.org Reporter: zeccav at gmail dot com Target Milestone: --- Running "make check" after building gcc the sanitizer complains that at unix.c:497 memcpy (buf, s->buffer + (s->logical_offset - s->buffer_offset), nbyte); the pointer buf == NULL but nbyte == 0 so it should be harmless. I believe that if(nbyte) memcpy (buf, s->buffer + (s->logical_offset - s->buffer_offset), nbyte); should avoid this undefined behaviour.