RDMA/mlx5: Do not allow the user to write to the clock page

commit c660133c339f9ab684fdf568c0d51b9ae5e86002 upstream.

The intent of this VMA was to be read-only from user space, but the
VM_MAYWRITE masking was missed, so mprotect could make it writable.

Cc: stable@vger.kernel.org
Fixes: 5c99eaecb1fc ("IB/mlx5: Mmap the HCA's clock info to user-space")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 50be240..8cc4da6 100644 (file)
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -2014,6 +2014,7 @@ static int mlx5_ib_mmap_clock_info_page(struct mlx5_ib_dev *dev,
 
        if (vma->vm_flags & VM_WRITE)
                return -EPERM;
+       vma->vm_flags &= ~VM_MAYWRITE;
 
        if (!dev->mdev->clock_info_page)
                return -EOPNOTSUPP;
@@ -2197,6 +2198,7 @@ static int mlx5_ib_mmap(struct ib_ucontext *ibcontext, struct vm_area_struct *vm
 
                if (vma->vm_flags & VM_WRITE)
                        return -EPERM;
+               vma->vm_flags &= ~VM_MAYWRITE;
 
                /* Don't expose to user-space information it shouldn't have */
                if (PAGE_SIZE > 4096)