ok: unsafe memcmp() usage correctly detected with '__read_overflow' in lib/test_fortify/read_overflow-memcmp.c
lib/test_fortify/test_fortify.h: In function 'do_fortify_tests':
lib/test_fortify/read_overflow-memcmp.c:3:9: error: statement with no effect [-Werror=unused-value]
    3 |         memcmp(small, large, sizeof(small) + 1)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/test_fortify/test_fortify.h:34:9: note: in expansion of macro 'TEST'
   34 |         TEST;
      |         ^~~~
In file included from ./include/linux/string.h:254,
                 from ./include/linux/bitmap.h:11,
                 from ./include/linux/cpumask.h:12,
                 from ./include/linux/smp.h:13,
                 from ./include/linux/lockdep.h:14,
                 from ./include/linux/spinlock.h:63,
                 from ./include/linux/mmzone.h:8,
                 from ./include/linux/gfp.h:7,
                 from ./include/linux/slab.h:16,
                 from lib/test_fortify/test_fortify.h:4,
                 from lib/test_fortify/read_overflow-memcmp.c:5:
In function 'memcmp',
    inlined from 'do_fortify_tests' at lib/test_fortify/test_fortify.h:34:2:
./include/linux/fortify-string.h:722:25: error: call to '__read_overflow' declared with attribute error: detected read beyond size of object (1st parameter)
  722 |                         __read_overflow();
      |                         ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors