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.

1 files changed, 1 insertions, 1 deletions

diff --git a/vm.c b/vm.c
index d9aaa7e..764512c 100644
--- 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)