[PATCH] mm/vma: Add VM_WARN_ON for commit_merge

[Liu Ye]

    Add VM_WARN_ON to prevent 'adjust' from accessing NULL pointers
    when 'adjust' is NULL and 'expanded' is false or 'adj_start' is
    not zero.
Signed-off-by: Liu Ye <liuye@xxxxxxxxxx>
---
 mm/vma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/vma.c b/mm/vma.c
index 31c9c6f51c9f..36b5ac675504 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -641,6 +641,7 @@ static int commit_merge(struct vma_merge_struct *vmg,
 
 	init_multi_vma_prep(&vp, vmg->vma, adjust, remove, remove2);
 
+	VM_WARN_ON(!adjust && (!expanded || adj_start));
 	VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
 		   vp.anon_vma != adjust->anon_vma);
 
-- 
2.25.1