RDMA/mlx5: Use memset_after() to zero struct mlx5_ib_mr

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Use memset_after() to zero the end of struct mlx5_ib_mr that should be
initialized.

Link: https://lore.kernel.org/r/20211213223331.135412-10-keescook@chromium.org
Acked-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 4a7a56ed740b9b35e84b40e870ec70e7cf7feffd..ded10719b6437b9270c933c4896bb8f5ae78197e 100644 (file)
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -664,8 +664,8 @@ struct mlx5_ib_mr {
 
        /* User MR data */
        struct mlx5_cache_ent *cache_ent;
+       /* Everything after cache_ent is zero'd when MR allocated */
 
-       /* This is zero'd when the MR is allocated */
        union {
                /* Used only while the MR is in the cache */
                struct {
@@ -718,7 +718,7 @@ struct mlx5_ib_mr {
 /* Zero the fields in the mr that are variant depending on usage */
 static inline void mlx5_clear_mr(struct mlx5_ib_mr *mr)
 {
-       memset(mr->out, 0, sizeof(*mr) - offsetof(struct mlx5_ib_mr, out));
+       memset_after(mr, 0, cache_ent);
 }
 
 static inline bool is_odp_mr(struct mlx5_ib_mr *mr)