vm: fix vm_pgoff wrap in stack expansion

[pandora-kernel.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index 2ec8eb5..8c05e5b 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1814,11 +1814,14 @@ static int expand_downwards(struct vm_area_struct *vma,
                size = vma->vm_end - address;
                grow = (vma->vm_start - address) >> PAGE_SHIFT;
 
-               error = acct_stack_growth(vma, size, grow);
-               if (!error) {
-                       vma->vm_start = address;
-                       vma->vm_pgoff -= grow;
-                       perf_event_mmap(vma);
+               error = -ENOMEM;
+               if (grow <= vma->vm_pgoff) {
+                       error = acct_stack_growth(vma, size, grow);
+                       if (!error) {
+                               vma->vm_start = address;
+                               vma->vm_pgoff -= grow;
+                               perf_event_mmap(vma);
+                       }
                }
        }
        vma_unlock_anon_vma(vma);