The userspace side on MW made a mistake and never actually used the udata
driver structure that was defined so it always passes 0 length. Keep the
kernel structure but this conversion has to permit 0 length as well.

Signed-off-by: Jason Gunthorpe <[email protected]>
---
 drivers/infiniband/hw/mlx5/mr.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index cbe34251e340b9..3ef467ac9e3d15 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1774,16 +1774,13 @@ int mlx5_ib_alloc_mw(struct ib_mw *ibmw, struct 
ib_udata *udata)
                __u32   response_length;
        } resp = {};
 
-       err = ib_copy_from_udata(&req, udata, min(udata->inlen, sizeof(req)));
-       if (err)
-               return err;
+       if (udata->inlen) {
+               err = ib_copy_validate_udata_in_cm(udata, req, reserved2, 0);
+               if (err)
+                       return err;
+       }
 
-       if (req.comp_mask || req.reserved1 || req.reserved2)
-               return -EOPNOTSUPP;
-
-       if (udata->inlen > sizeof(req) &&
-           !ib_is_udata_cleared(udata, sizeof(req),
-                                udata->inlen - sizeof(req)))
+       if (req.reserved1 || req.reserved2)
                return -EOPNOTSUPP;
 
        ndescs = req.num_klms ? roundup(req.num_klms, 4) : roundup(1, 4);
-- 
2.43.0


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