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From:   Kees Cook <keescook@chromium.org>
To:     linux-kernel@vger.kernel.org
Cc:     Kees Cook <keescook@chromium.org>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Max Gurtovoy <maxg@mellanox.com>, linux-rdma@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev,
        linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        linux-hardening@vger.kernel.org
Subject: [PATCH v2 48/63] IB/mthca: Use memset_startat() for clearing mpt_entry
Date:   Tue, 17 Aug 2021 23:05:18 -0700
Message-Id: <20210818060533.3569517-49-keescook@chromium.org>
In-Reply-To: <20210818060533.3569517-1-keescook@chromium.org>
References: <20210818060533.3569517-1-keescook@chromium.org>
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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 ce0e0867e488..1208e92ca3d3 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_startat(mpt_entry, 0, lkey);
 
 	if (mr->mtt)
 		mpt_entry->mtt_seg =
-- 
2.30.2