mm: fix corner case in anon_vma endless growing prevention

[cascardo/linux.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 7b36aa7..7f684d5 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -778,10 +778,12 @@ again:                    remove_next = 1 + (end > next->vm_end);
                if (exporter && exporter->anon_vma && !importer->anon_vma) {
                        int error;
 
+                       importer->anon_vma = exporter->anon_vma;
                        error = anon_vma_clone(importer, exporter);
-                       if (error)
+                       if (error) {
+                               importer->anon_vma = NULL;
                                return error;
-                       importer->anon_vma = exporter->anon_vma;
+                       }
                }
        }
 
@@ -2099,14 +2101,17 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
 {
        struct mm_struct *mm = vma->vm_mm;
        struct rlimit *rlim = current->signal->rlim;
-       unsigned long new_start;
+       unsigned long new_start, actual_size;
 
        /* address space limit tests */
        if (!may_expand_vm(mm, grow))
                return -ENOMEM;
 
        /* Stack limit test */
-       if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
+       actual_size = size;
+       if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
+               actual_size -= PAGE_SIZE;
+       if (actual_size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
                return -ENOMEM;
 
        /* mlock limit tests */