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

[Liam R. Howlett]

Andrew,

Just in case you didn't notice, this patch was reviewed on another list.

Thanks,
Liam

* Hajime Tazaki <thehajime at gmail.com> [241108 17:29]:
> 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
>