[PATCH 14/17] IB/mthca: Use memset_startat() for clearing mpt_entry

Kees Cook
2021-12-13T22:34:08Z

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

Use memset_startat() so memset() doesn't get confused about writing
beyond the destination member that is intended to be the starting point
of zeroing through the end of the struct.

Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Max Gurtovoy <maxg@mellanox.com>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/infiniband/hw/mthca/mthca_mr.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/mthca/mthca_mr.c b/drivers/infiniband/hw/mthca/mthca_mr.c
index a59100c496b4..192f83fd7c8a 100644
--- a/drivers/infiniband/hw/mthca/mthca_mr.c
+++ b/drivers/infiniband/hw/mthca/mthca_mr.c
@@ -467,8 +467,7 @@ int mthca_mr_alloc(struct mthca_dev *dev, u32 pd, int buffer_size_shift,
mpt_entry->start = cpu_to_be64(iova);
mpt_entry->length = cpu_to_be64(total_size);

- memset(&mpt_entry->lkey, 0,
- sizeof *mpt_entry - offsetof(struct mthca_mpt_entry, lkey));
+ memset_startat(mpt_entry, 0, lkey);

if (mr->mtt)
mpt_entry->mtt_seg =
--
2.30.2