Added sanity checks for mb pointers

kernel/kernel/kernel.c

@@ -23,6 +23,9 @@ void kmain(multiboot_info_t *mb_info, uint32_t mb_magic) {
     if (mb_magic != MULTIBOOT_BOOTLOADER_MAGIC)
         panic("Not a multiboot bootloader!");
 
+    if (!mb_info)
+        panic("Invalid multiboot pointer");
+
     print_memory_map(mb_info);
     puts("");
     print_kernel_map();

kernel/pmm/src/mmap.c

@@ -1,4 +1,5 @@
 #include "kernel/pmm.h"
+#include "kernel/multiboot.h"
 
 #include <stdio.h>
 #include <stdint.h>
@@ -26,6 +27,13 @@ static char *mem_types[] = {
 
 void print_memory_map(multiboot_info_t *mb_info) {
 
+    if (!(mb_info->flags & MULTIBOOT_INFO_MEM_MAP)) {
+
+        puts("There is no info about memory map");
+        return;
+
+    }
+
     printf("Physical Memory Map:\n");
 
     multiboot_memory_map_t *mmap =