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From:   Kees Cook <keescook@chromium.org>
To:     linux-kernel@vger.kernel.org
Cc:     Kees Cook <keescook@chromium.org>, Jouni Malinen <j@w1.fi>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Allen Pais <allen.lkml@gmail.com>,
        Romain Perier <romain.perier@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Vaibhav Gupta <vaibhavgupta40@gmail.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev,
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        clang-built-linux@googlegroups.com,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        linux-hardening@vger.kernel.org
Subject: [PATCH v2 15/63] intersil: Use struct_group() for memcpy() region
Date:   Tue, 17 Aug 2021 23:04:45 -0700
Message-Id: <20210818060533.3569517-16-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 memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

Use struct_group() in struct hfa384x_tx_frame around members
frame_control, duration_id, addr1, addr2, addr3, and seq_ctrl, so they
can be referenced together. This will allow memcpy() and sizeof() to
more easily reason about sizes, improve readability, and avoid future
warnings about writing beyond the end of frame_control.

"pahole" shows no size nor member offset changes to struct
hfa384x_tx_frame. "objdump -d" shows no object code changes.

Cc: Jouni Malinen <j@w1.fi>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Allen Pais <allen.lkml@gmail.com>
Cc: Romain Perier <romain.perier@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/wireless/intersil/hostap/hostap_hw.c   |  5 +++--
 drivers/net/wireless/intersil/hostap/hostap_wlan.h | 14 ++++++++------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/intersil/hostap/hostap_hw.c b/drivers/net/wireless/intersil/hostap/hostap_hw.c
index 9a19046217df..cea8a9ddc4da 100644
--- a/drivers/net/wireless/intersil/hostap/hostap_hw.c
+++ b/drivers/net/wireless/intersil/hostap/hostap_hw.c
@@ -1812,8 +1812,9 @@ static int prism2_tx_80211(struct sk_buff *skb, struct net_device *dev)
 	memset(&txdesc, 0, sizeof(txdesc));
 
 	/* skb->data starts with txdesc->frame_control */
-	hdr_len = 24;
-	skb_copy_from_linear_data(skb, &txdesc.frame_control, hdr_len);
+	hdr_len = sizeof(txdesc.frame);
+	BUILD_BUG_ON(hdr_len != 24);
+	skb_copy_from_linear_data(skb, &txdesc.frame, hdr_len);
 	if (ieee80211_is_data(txdesc.frame_control) &&
 	    ieee80211_has_a4(txdesc.frame_control) &&
 	    skb->len >= 30) {
diff --git a/drivers/net/wireless/intersil/hostap/hostap_wlan.h b/drivers/net/wireless/intersil/hostap/hostap_wlan.h
index dd2603d9b5d3..174735a137c5 100644
--- a/drivers/net/wireless/intersil/hostap/hostap_wlan.h
+++ b/drivers/net/wireless/intersil/hostap/hostap_wlan.h
@@ -115,12 +115,14 @@ struct hfa384x_tx_frame {
 	__le16 tx_control; /* HFA384X_TX_CTRL_ flags */
 
 	/* 802.11 */
-	__le16 frame_control; /* parts not used */
-	__le16 duration_id;
-	u8 addr1[ETH_ALEN];
-	u8 addr2[ETH_ALEN]; /* filled by firmware */
-	u8 addr3[ETH_ALEN];
-	__le16 seq_ctrl; /* filled by firmware */
+	struct_group(frame,
+		__le16 frame_control; /* parts not used */
+		__le16 duration_id;
+		u8 addr1[ETH_ALEN];
+		u8 addr2[ETH_ALEN]; /* filled by firmware */
+		u8 addr3[ETH_ALEN];
+		__le16 seq_ctrl; /* filled by firmware */
+	);
 	u8 addr4[ETH_ALEN];
 	__le16 data_len;
 
-- 
2.30.2