[Bug libfortran/67540] New: string_intrinsics_inc.c sanitizer detects null pointer passed to memcpy

["zeccav at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67540

            Bug ID: 67540
           Summary: string_intrinsics_inc.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: ---

During make check-fortran in gcc build the sanitizer complains
that a null pointer is passed to memcpy in string_intrinsics_inc.c:89

res = MEMCMP (s1, s2, ((len1 < len2) ? len1 : len2));

string_intrinsics_inc.c:90:7: runtime error: null pointer passed as argument 1,
which is declared to never be null

because s1 == NULL

My fix is

int lvz=len1 < len2 ? len1 : len2;
if(lvz) res = MEMCMP (s1, s2, lvz); else res=0;