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From:   Dmitry Antipov <dmantipov@yandex.ru>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Kalle Valo <kvalo@kernel.org>, linux-wireless@vger.kernel.org,
        Dmitry Antipov <dmantipov@yandex.ru>
Subject: [PATCH] wifi: wil6210: fix fortify warnings
Date:   Wed, 21 Jun 2023 12:36:55 +0300
Message-ID: <20230621093711.80118-1-dmantipov@yandex.ru>
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When compiling with gcc 13.1 and CONFIG_FORTIFY_SOURCE=y,
I've noticed the following:

In function ‘fortify_memcpy_chk’,
    inlined from ‘wil_rx_crypto_check_edma’ at drivers/net/wireless/ath/wil6210/txrx_edma.c:566:2:
./include/linux/fortify-string.h:529:25: warning: call to ‘__read_overflow2_field’
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Wattribute-warning]
  529 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

where the compiler complains on:

const u8 *pn;
...
pn = (u8 *)&st->ext.pn_15_0;
...
memcpy(cc->pn, pn, IEEE80211_GCMP_PN_LEN);

and:

In function ‘fortify_memcpy_chk’,
    inlined from ‘wil_rx_crypto_check’ at drivers/net/wireless/ath/wil6210/txrx.c:684:2:
./include/linux/fortify-string.h:529:25: warning: call to ‘__read_overflow2_field’
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Wattribute-warning]
  529 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

where the compiler complains on:

const u8 *pn = (u8 *)&d->mac.pn_15_0;
...
memcpy(cc->pn, pn, IEEE80211_GCMP_PN_LEN);

In both cases, the fortification logic interprets 'memcpy()' as 6-byte
overread of 2-byte field 'pn_15_0' of 'struct wil_rx_status_extension'
and 'pn_15_0' of 'struct vring_rx_mac', respectively. To silence
these warnings, last two fields of the aforementioned structures
are grouped using 'struct_group_attr(pn, __packed' quirk.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
 drivers/net/wireless/ath/wil6210/txrx.c      | 2 +-
 drivers/net/wireless/ath/wil6210/txrx.h      | 6 ++++--
 drivers/net/wireless/ath/wil6210/txrx_edma.c | 2 +-
 drivers/net/wireless/ath/wil6210/txrx_edma.h | 6 ++++--
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/wil6210/txrx.c b/drivers/net/wireless/ath/wil6210/txrx.c
index 237cbd5c5060..f29ac6de7139 100644
--- a/drivers/net/wireless/ath/wil6210/txrx.c
+++ b/drivers/net/wireless/ath/wil6210/txrx.c
@@ -666,7 +666,7 @@ static int wil_rx_crypto_check(struct wil6210_priv *wil, struct sk_buff *skb)
 	struct wil_tid_crypto_rx *c = mc ? &s->group_crypto_rx :
 				      &s->tid_crypto_rx[tid];
 	struct wil_tid_crypto_rx_single *cc = &c->key_id[key_id];
-	const u8 *pn = (u8 *)&d->mac.pn_15_0;
+	const u8 *pn = (u8 *)&d->mac.pn;
 
 	if (!cc->key_set) {
 		wil_err_ratelimited(wil,
diff --git a/drivers/net/wireless/ath/wil6210/txrx.h b/drivers/net/wireless/ath/wil6210/txrx.h
index 1ae1bec1b97f..689f68d89a44 100644
--- a/drivers/net/wireless/ath/wil6210/txrx.h
+++ b/drivers/net/wireless/ath/wil6210/txrx.h
@@ -343,8 +343,10 @@ struct vring_rx_mac {
 	u32 d0;
 	u32 d1;
 	u16 w4;
-	u16 pn_15_0;
-	u32 pn_47_16;
+	struct_group_attr(pn, __packed,
+		u16 pn_15_0;
+		u32 pn_47_16;
+	);
 } __packed;
 
 /* Rx descriptor - DMA part
diff --git a/drivers/net/wireless/ath/wil6210/txrx_edma.c b/drivers/net/wireless/ath/wil6210/txrx_edma.c
index 201c8c35e0c9..1ba1f21ebea2 100644
--- a/drivers/net/wireless/ath/wil6210/txrx_edma.c
+++ b/drivers/net/wireless/ath/wil6210/txrx_edma.c
@@ -548,7 +548,7 @@ static int wil_rx_crypto_check_edma(struct wil6210_priv *wil,
 	s = &wil->sta[cid];
 	c = mc ? &s->group_crypto_rx : &s->tid_crypto_rx[tid];
 	cc = &c->key_id[key_id];
-	pn = (u8 *)&st->ext.pn_15_0;
+	pn = (u8 *)&st->ext.pn;
 
 	if (!cc->key_set) {
 		wil_err_ratelimited(wil,
diff --git a/drivers/net/wireless/ath/wil6210/txrx_edma.h b/drivers/net/wireless/ath/wil6210/txrx_edma.h
index c736f7413a35..ee90e225bb05 100644
--- a/drivers/net/wireless/ath/wil6210/txrx_edma.h
+++ b/drivers/net/wireless/ath/wil6210/txrx_edma.h
@@ -330,8 +330,10 @@ struct wil_rx_status_extension {
 	u32 d0;
 	u32 d1;
 	__le16 seq_num; /* only lower 12 bits */
-	u16 pn_15_0;
-	u32 pn_47_16;
+	struct_group_attr(pn, __packed,
+		u16 pn_15_0;
+		u32 pn_47_16;
+	);
 } __packed;
 
 struct wil_rx_status_extended {
-- 
2.41.0