vm: fix vm_pgoff wrap in upward expansion

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 <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index e27e0cf0de03..772140c53ab1 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);