On Thu, Aug 19, 2021 at 09:27:16AM -0300, Jason Gunthorpe wrote:
On Tue, Aug 17, 2021 at 11:05:26PM -0700, Kees Cook wrote:
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields.
Add struct_group() to mark region of struct mlx5_ib_mr that should be initialized to zero.
Cc: Leon Romanovsky leon@kernel.org Cc: Doug Ledford dledford@redhat.com Cc: Jason Gunthorpe jgg@ziepe.ca Cc: linux-rdma@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org
drivers/infiniband/hw/mlx5/mlx5_ib.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h index bf20a388eabe..f63bf204a7a1 100644 --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h @@ -644,6 +644,7 @@ struct mlx5_ib_mr { struct ib_umem *umem;
/* This is zero'd when the MR is allocated */
- struct_group(cleared, union { /* Used only while the MR is in the cache */ struct {
@@ -691,12 +692,13 @@ struct mlx5_ib_mr { bool is_odp_implicit; }; };
- );
};
/* 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(&mr->cleared, 0, sizeof(mr->cleared));
}
Why not use the memset_after(mr->umem) here?
I can certainly do that instead. In this series I've tended to opt for groupings so the position of future struct member additions are explicitly chosen. (i.e. reducing the chance that a zeroing of the new member be a surprise.)
-Kees