[PATCH 46/64] IB/mthca: Use memset_after() for clearing mpt_entry

Kees Cook
2021-07-27T21:18:50Z

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() 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.

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 ce0e0867e488..64adba5c067d 100644
--- a/drivers/infiniband/hw/mthca/mthca_mr.c
+++ b/drivers/infiniband/hw/mthca/mthca_mr.c
@@ -469,8 +469,7 @@ 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_after(mpt_entry, 0, length);

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