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   THE MARTYR OF BUTLERIAN JIHAD (icon_of_computational_sin@mstdn.starnix.network)'s status on Wednesday, 18-Sep-2024 18:33:47 JST THE MARTYR OF BUTLERIAN JIHAD

   Even though NULL is the holy cow of C programmers, treated very specially by C compilers, technically nothing stops you from doing this.

   ~ sudo sysctl vm.mmap_min_addr=0
   vm.mmap_min_addr = 0

   ~ cat null.c
   #include
   #include
   #include

   int main(void) {
   char *addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED|MAP_ANONYMOUS, -1, 0);
   if (addr == MAP_FAILED) {
   perror("mmap");
   return 1;
   }
   printf("We have successfully mapped %p\n", addr);
   strcpy(addr, "ON NOES YOU HAVE WORMS IN YOUR NULL");
   printf("%s\n", NULL);
   }
   ~ gcc null.c -o null
   ~ ./null
   
   We have successfully mapped (nil)
   ON NOES YOU HAVE WORMS IN YOUR NULL

   WHERE IS YOUR GOD NOW?