selftests/resctrl: Return NULL if malloc_and_init_memory() did not alloc mem

malloc_and_init_memory() in fill_buf isn't checking if memalign()
successfully allocated memory or not before accessing the memory.

Check the return value of memalign() and return NULL if allocating
aligned memory fails.

Fixes: a2561b12 ("selftests/resctrl: Add built in benchmark")
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/resctrl/fill_buf.c

@@ -68,6 +68,8 @@ static void *malloc_and_init_memory(size_t s)
 	size_t s64;
 
 	void *p = memalign(PAGE_SIZE, s);
+	if (!p)
+		return NULL;
 
 	p64 = (uint64_t *)p;
 	s64 = s / sizeof(uint64_t);