linux-kernel - [PATCH AUTOSEL 5.4 1/9] wifi: mac80211_hwsim: fix clang-specific fortify warning

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Message-ID: <20231107121256.3758858-1-sashal@kernel.org>
Date:   Tue,  7 Nov 2023 07:12:44 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dmitry Antipov <dmantipov@...dex.ru>,
        Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <sashal@...nel.org>, kvalo@...nel.org,
        nathan@...nel.org, ndesaulniers@...gle.com,
        linux-wireless@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH AUTOSEL 5.4 1/9] wifi: mac80211_hwsim: fix clang-specific fortify warning

From: Dmitry Antipov <dmantipov@...dex.ru>

[ Upstream commit cbaccdc42483c65016f1bae89128c08dc17cfb2a ]

When compiling with clang 16.0.6 and CONFIG_FORTIFY_SOURCE=y, I've
noticed the following (somewhat confusing due to absence of an actual
source code location):

In file included from drivers/net/wireless/virtual/mac80211_hwsim.c:18:
In file included from ./include/linux/slab.h:16:
In file included from ./include/linux/gfp.h:7:
In file included from ./include/linux/mmzone.h:8:
In file included from ./include/linux/spinlock.h:56:
In file included from ./include/linux/preempt.h:79:
In file included from ./arch/x86/include/asm/preempt.h:9:
In file included from ./include/linux/thread_info.h:60:
In file included from ./arch/x86/include/asm/thread_info.h:53:
In file included from ./arch/x86/include/asm/cpufeature.h:5:
In file included from ./arch/x86/include/asm/processor.h:23:
In file included from ./arch/x86/include/asm/msr.h:11:
In file included from ./arch/x86/include/asm/cpumask.h:5:
In file included from ./include/linux/cpumask.h:12:
In file included from ./include/linux/bitmap.h:11:
In file included from ./include/linux/string.h:254:
./include/linux/fortify-string.h:592:4: warning: call to '__read_overflow2_field'
declared with 'warning' attribute: detected read beyond size of field (2nd
parameter); maybe use struct_group()? [-Wattribute-warning]
                        __read_overflow2_field(q_size_field, size);

The compiler actually complains on 'mac80211_hwsim_get_et_strings()' where
fortification logic inteprets call to 'memcpy()' as an attempt to copy the
whole 'mac80211_hwsim_gstrings_stats' array from its first member and so
issues an overread warning. This warning may be silenced by passing
an address of the whole array and not the first member to 'memcpy()'.

Signed-off-by: Dmitry Antipov <dmantipov@...dex.ru>
Link: https://lore.kernel.org/r/20230829094140.234636-1-dmantipov@yandex.ru
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/mac80211_hwsim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index a21739b2f44e6..634e8c1e71cca 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -2323,7 +2323,7 @@ static void mac80211_hwsim_get_et_strings(struct ieee80211_hw *hw,
 					  u32 sset, u8 *data)
 {
 	if (sset == ETH_SS_STATS)
-		memcpy(data, *mac80211_hwsim_gstrings_stats,
+		memcpy(data, mac80211_hwsim_gstrings_stats,
 		       sizeof(mac80211_hwsim_gstrings_stats));
 }
 
-- 
2.42.0