mremap: don't leak new_vma if f_op->mremap() fails

move_vma() can't just return if f_op->mremap() fails, we should unmap the
new vma like we do if move_page_tables() fails.  To avoid the code
duplication this patch moves the "move entries back" under the new "if
(err)" branch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mremap.c b/mm/mremap.c
index a7c93eceb1c8d1ce59235d47ec7e49df4efefb86..f54a43fa4b79886cac7d0066dbc1968e98dfadea 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -276,6 +276,12 @@ static unsigned long move_vma(struct vm_area_struct *vma,
        moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len,
                                     need_rmap_locks);
        if (moved_len < old_len) {
+               err = -ENOMEM;
+       } else if (vma->vm_file && vma->vm_file->f_op->mremap) {
+               err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
+       }
+
+       if (unlikely(err)) {
                /*
                 * On error, move entries back from new area to old,
                 * which will succeed since page tables still there,
@@ -286,16 +292,8 @@ static unsigned long move_vma(struct vm_area_struct *vma,
                vma = new_vma;
                old_len = new_len;
                old_addr = new_addr;
-               new_addr = -ENOMEM;
+               new_addr = err;
        } else {
-               if (vma->vm_file && vma->vm_file->f_op->mremap) {
-                       err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma);
-                       if (err < 0) {
-                               move_page_tables(new_vma, new_addr, vma,
-                                                old_addr, moved_len, true);
-                               return err;
-                       }
-               }
                arch_remap(mm, old_addr, old_addr + old_len,
                           new_addr, new_addr + new_len);
        }