Re: [PATCH for-rc] RDMA/hfi1: Fix use-after-free bug for mm struct

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Apr 08, 2022 at 09:35:23AM -0400, Dennis Dalessandro wrote:
> From: Douglas Miller <doug.miller@cornelisnetworks.com>
> 
> Under certain conditions, such as MPI_Abort, the hfi1 cleanup
> code may represent the last reference held on the task mm.
> hfi1_mmu_rb_unregister() then drops the last reference and the mm is
> freed before the final use in hfi1_release_user_pages().  A new task
> may allocate the mm structure while it is still being used, resulting in
> problems. One manifestation is corruption of the mmap_sem counter leading
> to a hang in down_write().  Another is corruption of an mm struct that
> is in use by another task.
> 
> Fixes: 3d2a9d642512 ("IB/hfi1: Ensure correct mm is used at all times")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Douglas Miller <doug.miller@cornelisnetworks.com>
> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
> ---
>  drivers/infiniband/hw/hfi1/mmu_rb.c |    6 ++++++
>  1 file changed, 6 insertions(+)

Applied to for-rc, thanks

Jason