fix possible memory leak in deallocuvm

when a zero PDE is encountered while searching for present PTEs to free, resume searching at first entry of the next page table instead of the current entry of the next page table.
jiraiyew · Sep 26, 2016 · ffe4449 · ffe4449
1 parent 91fd347
commit ffe4449
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/vm.c b/vm.c
@@ -266,7 +266,7 @@ deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
   for(; a  < oldsz; a += PGSIZE){
     pte = walkpgdir(pgdir, (char*)a, 0);
     if(!pte)
-      a += (NPTENTRIES - 1) * PGSIZE;
+      a = PGADDR(PDX(a) + 1, 0, 0) - PGSIZE;
     else if((*pte & PTE_P) != 0){
       pa = PTE_ADDR(*pte);
       if(pa == 0)