[PATCH v2 15/63] intersil: Use struct_group() for memcpy() region

Kees Cook
2021-08-18T06:18:23Z

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