https://bugs.winehq.org/show_bug.cgi?id=50842
--- Comment #8 from Robert Wilhelm sloper42@yahoo.com --- @Bernhard: No useful information for you in the log.
drmemory log only confirms what you already pointed out in comment 1: null pointer access in mov (%rcx),%rax with stacktrace completely in msado15_test.exe. It does not give any hints where the variable got overwritten.