From: Hugh Dickins <[email protected]>

Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed
the case of an expanding mapping causing vm_pgoff wrapping when you had
downward stack expansion.  But there was another case where IA64 and
PA-RISC expand mappings: upward expansion.

This fixes that case too.

Signed-off-by: Hugh Dickins <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
---
 mm/mmap.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index e27e0cf..772140c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1767,10 +1767,13 @@ int expand_upwards(struct vm_area_struct *vma, unsigned 
long address)
                size = address - vma->vm_start;
                grow = (address - vma->vm_end) >> PAGE_SHIFT;
 
-               error = acct_stack_growth(vma, size, grow);
-               if (!error) {
-                       vma->vm_end = address;
-                       perf_event_mmap(vma);
+               error = -ENOMEM;
+               if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+                       error = acct_stack_growth(vma, size, grow);
+                       if (!error) {
+                               vma->vm_end = address;
+                               perf_event_mmap(vma);
+                       }
                }
        }
        vma_unlock_anon_vma(vma);
-- 
1.7.4.1

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