[PATCH 12/17] iw_cxgb4: Use memset_startat() for cpl_t5_pass_accept_rpl

Kees Cook
2021-12-13T22:34:01Z

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. Additionally, since everything
appears to perform a roundup (including allocation), just change the
size of the struct itself and add a build-time check to validate the
expected size.

Cc: Potnuri Bharat Teja <bharat@chelsio.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Raju Rangoju <rajur@chelsio.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-rdma@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/infiniband/hw/cxgb4/cm.c | 5 +++--
drivers/net/ethernet/chelsio/cxgb4/t4_msg.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 913f39ee4416..c16017f6e8db 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -2471,7 +2471,8 @@ static int accept_cr(struct c4iw_ep *ep, struct sk_buff *skb,
skb_get(skb);
rpl = cplhdr(skb);
if (!is_t4(adapter_type)) {
- skb_trim(skb, roundup(sizeof(*rpl5), 16));
+ BUILD_BUG_ON(sizeof(*rpl5) != roundup(sizeof(*rpl5), 16));
+ skb_trim(skb, sizeof(*rpl5));
rpl5 = (void *)rpl;
INIT_TP_WR(rpl5, ep->hwtid);
} else {
@@ -2487,7 +2488,7 @@ static int accept_cr(struct c4iw_ep *ep, struct sk_buff *skb,
opt2 |= CONG_CNTRL_V(CONG_ALG_TAHOE);
opt2 |= T5_ISS_F;
rpl5 = (void *)rpl;
- memset(&rpl5->iss, 0, roundup(sizeof(*rpl5)-sizeof(*rpl), 16));
+ memset_after(rpl5, 0, iss);
if (peer2peer)
isn += 4;
rpl5->iss = cpu_to_be32(isn);
diff --git a/drivers/net/ethernet/chelsio/cxgb4/t4_msg.h b/drivers/net/ethernet/chelsio/cxgb4/t4_msg.h
index fed5f93bf620..26433a62d7f0 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/t4_msg.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/t4_msg.h
@@ -497,7 +497,7 @@ struct cpl_t5_pass_accept_rpl {
__be32 opt2;
__be64 opt0;
__be32 iss;
- __be32 rsvd;
+ __be32 rsvd[3];
};

struct cpl_act_open_req {
--
2.30.2