[PATCH rdma-next 1/6] RDMA/mlx5: Do not allow the user to write to the clock page

[Leon Romanovsky]

From: Jason Gunthorpe <j...@mellanox.com>

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: sta...@vger.kernel.org
Fixes: 5c99eaecb1fc ("IB/mlx5: Mmap the HCA's clock info to user-space")
Signed-off-by: Jason Gunthorpe <j...@mellanox.com>
Reviewed-by: Haggai Eran <hagg...@mellanox.com>
Signed-off-by: Leon Romanovsky <leo...@mellanox.com>
---
 drivers/infiniband/hw/mlx5/main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/infiniband/hw/mlx5/main.c 
b/drivers/infiniband/hw/mlx5/main.c
index 15676a149680..73b7f9636f82 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -2072,6 +2072,7 @@ 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;
@@ -2237,6 +2238,7 @@ 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)
-- 
2.20.1