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

From: Leon Romanovsky <[email-masked]>
Date: Tue, 16 Apr 2019 14:07:25 +0300

From: Jason Gunthorpe <[email-masked]>

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: [email-masked]
Fixes: 5c99eaecb1fc ("IB/mlx5: Mmap the HCA's clock info to user-space")
Signed-off-by: Jason Gunthorpe <[email-masked]>
Reviewed-by: Haggai Eran <[email-masked]>
Signed-off-by: Leon Romanovsky <[email-masked]>
---
 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