[Bug sanitizer/61547] New: Invalid sanitization of trailing byte in __builtin_strlen

["y.gribov at samsung dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61547

            Bug ID: 61547
           Summary: Invalid sanitization of trailing byte in
                    __builtin_strlen
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: y.gribov at samsung dot com
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org

Created attachment 32963
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32963&action=edit
Reprocase

The attached testcase performs an overflow in strlen call. Current GCC fails to
detect it because of invalid instrumentation of trailing byte:
$ gcc repro.c -fsanitize=address -O1 -static-libasan
$ ./a.out
$ echo $?
0