[PATCH] nommu: pass NULL argument to vma_iter_prealloc()

[Hajime Tazaki]

When deleting a vma entry from a maple tree, it has to pass NULL to
vma_iter_prealloc() in order to calculate internal state of the tree,
but it passed a wrong argument.  As a result, nommu kernels crashed upon
accessing a vma iterator, such as acct_collect() reading the size of
vma entries after do_munmap().

This commit fixes this issue by passing a right argument to the
preallocation call.

Fixes: b5df09226450 ("mm: set up vma iterator for vma_iter_prealloc() calls")
Cc: stable at vger.kernel.org
Reviewed-by: Liam R. Howlett <Liam.Howlett at Oracle.com>
Signed-off-by: Hajime Tazaki <thehajime at gmail.com>
---
 mm/nommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/nommu.c b/mm/nommu.c
index 385b0c15add8..0c708f85408d 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -573,7 +573,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
 	VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start);
 
 	vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
-	if (vma_iter_prealloc(&vmi, vma)) {
+	if (vma_iter_prealloc(&vmi, NULL)) {
 		pr_warn("Allocation of vma tree for process %d failed\n",
 		       current->pid);
 		return -ENOMEM;
-- 
2.43.0