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From:   Dmitry Antipov <dmantipov@yandex.ru>
To:     Srinivasan Raju <srini.raju@purelifi.com>
Cc:     Kalle Valo <kvalo@kernel.org>, linux-wireless@vger.kernel.org,
        Dmitry Antipov <dmantipov@yandex.ru>
Subject: [PATCH] wifi: plfxlc: fix clang-specific fortify warning
Date:   Tue, 29 Aug 2023 12:45:31 +0300
Message-ID: <20230829094541.234751-1-dmantipov@yandex.ru>
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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/purelifi/plfxlc/mac.c:6:
In file included from ./include/linux/netdevice.h:24:
In file included from ./include/linux/timer.h:6:
In file included from ./include/linux/ktime.h:24:
In file included from ./include/linux/time.h:60:
In file included from ./include/linux/time32.h:13:
In file included from ./include/linux/timex.h:67:
In file included from ./arch/x86/include/asm/timex.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 'plfxlc_get_et_strings()' where
fortification logic inteprets call to 'memcpy()' as an attempt to copy
the whole 'et_strings' 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@yandex.ru>
---
 drivers/net/wireless/purelifi/plfxlc/mac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/purelifi/plfxlc/mac.c b/drivers/net/wireless/purelifi/plfxlc/mac.c
index 94ee831b5de3..506d2f31efb5 100644
--- a/drivers/net/wireless/purelifi/plfxlc/mac.c
+++ b/drivers/net/wireless/purelifi/plfxlc/mac.c
@@ -666,7 +666,7 @@ static void plfxlc_get_et_strings(struct ieee80211_hw *hw,
 				  u32 sset, u8 *data)
 {
 	if (sset == ETH_SS_STATS)
-		memcpy(data, *et_strings, sizeof(et_strings));
+		memcpy(data, et_strings, sizeof(et_strings));
 }
 
 static void plfxlc_get_et_stats(struct ieee80211_hw *hw,
-- 
2.41.0