linux-kernel - [PATCH AUTOSEL 6.6 05/21] wifi: ath9k: work around memset overflow warning

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Message-ID: <20240527141551.3853516-5-sashal@kernel.org>
Date: Mon, 27 May 2024 10:15:16 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Arnd Bergmann <arnd@...db.de>,
	Toke Høiland-Jørgensen <toke@...e.dk>,
	Kees Cook <keescook@...omium.org>,
	Kalle Valo <quic_kvalo@...cinc.com>,
	Sasha Levin <sashal@...nel.org>,
	kvalo@...nel.org,
	linux-wireless@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 05/21] wifi: ath9k: work around memset overflow warning

From: Arnd Bergmann <arnd@...db.de>

[ Upstream commit 61752ac69b69ed2e04444d090f6917c77ab36d42 ]

gcc-9 and some other older versions produce a false-positive warning
for zeroing two fields

In file included from include/linux/string.h:369,
                 from drivers/net/wireless/ath/ath9k/main.c:18:
In function 'fortify_memset_chk',
    inlined from 'ath9k_ps_wakeup' at drivers/net/wireless/ath/ath9k/main.c:140:3:
include/linux/fortify-string.h:462:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  462 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Using a struct_group seems to reliably avoid the warning and
not make the code much uglier. The combined memset() should even
save a couple of cpu cycles.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Toke Høiland-Jørgensen <toke@...e.dk>
Reviewed-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Kalle Valo <quic_kvalo@...cinc.com>
Link: https://msgid.link/20240328135509.3755090-3-arnd@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/ath/ath.h        | 6 ++++--
 drivers/net/wireless/ath/ath9k/main.c | 3 +--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath.h b/drivers/net/wireless/ath/ath.h
index f02a308a9ffc5..34654f710d8a1 100644
--- a/drivers/net/wireless/ath/ath.h
+++ b/drivers/net/wireless/ath/ath.h
@@ -171,8 +171,10 @@ struct ath_common {
 	unsigned int clockrate;
 
 	spinlock_t cc_lock;
-	struct ath_cycle_counters cc_ani;
-	struct ath_cycle_counters cc_survey;
+	struct_group(cc,
+		struct ath_cycle_counters cc_ani;
+		struct ath_cycle_counters cc_survey;
+	);
 
 	struct ath_regulatory regulatory;
 	struct ath_regulatory reg_world_copy;
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 1494feedb27db..aa271b82875e0 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -135,8 +135,7 @@ void ath9k_ps_wakeup(struct ath_softc *sc)
 	if (power_mode != ATH9K_PM_AWAKE) {
 		spin_lock(&common->cc_lock);
 		ath_hw_cycle_counters_update(common);
-		memset(&common->cc_survey, 0, sizeof(common->cc_survey));
-		memset(&common->cc_ani, 0, sizeof(common->cc_ani));
+		memset(&common->cc, 0, sizeof(common->cc));
 		spin_unlock(&common->cc_lock);
 	}
 
-- 
2.43.0