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From:   Dmitry Antipov <dmantipov@yandex.ru>
To:     Felix Fietkau <nbd@nbd.name>
Cc:     Kalle Valo <kvalo@kernel.org>, linux-mediatek@lists.infradead.org,
        linux-wireless@vger.kernel.org,
        Dmitry Antipov <dmantipov@yandex.ru>
Subject: [PATCH] wifi: mt76: fix clang-specific fortify warnings
Date:   Tue, 29 Aug 2023 12:43:49 +0300
Message-ID: <20230829094353.234713-1-dmantipov@yandex.ru>
MIME-Version: 1.0
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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/mediatek/mt76/mt792x_core.c:4:
In file included from ./include/linux/module.h:13:
In file included from ./include/linux/stat.h:19:
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);

In file included from drivers/net/wireless/mediatek/mt76/mt7915/main.c:4:
In file included from ./include/linux/etherdevice.h:20:
In file included from ./include/linux/if_ether.h:19:
In file included from ./include/linux/skbuff.h:15:
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);

In file included from drivers/net/wireless/mediatek/mt76/mt7996/main.c:6:
In file included from drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h:9:
In file included from ./include/linux/interrupt.h:8:
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 'mt7915_get_et_strings()',
'mt792x_get_et_strings()' and 'mt7996_get_et_strings()' due to the same
reason: fortification logic inteprets call to 'memcpy()' as an attempt
to copy the whole array from its first member and so issues an overread
warning. These warnings 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/mediatek/mt76/mt7915/main.c | 2 +-
 drivers/net/wireless/mediatek/mt76/mt792x_core.c | 2 +-
 drivers/net/wireless/mediatek/mt76/mt7996/main.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/main.c b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
index 8ebbf186fab2..53348dd80c3b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
@@ -1386,7 +1386,7 @@ void mt7915_get_et_strings(struct ieee80211_hw *hw,
 	if (sset != ETH_SS_STATS)
 		return;
 
-	memcpy(data, *mt7915_gstrings_stats, sizeof(mt7915_gstrings_stats));
+	memcpy(data, mt7915_gstrings_stats, sizeof(mt7915_gstrings_stats));
 	data += sizeof(mt7915_gstrings_stats);
 	page_pool_ethtool_stats_get_strings(data);
 }
diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_core.c b/drivers/net/wireless/mediatek/mt76/mt792x_core.c
index 46be7f996c7e..81f316ddc111 100644
--- a/drivers/net/wireless/mediatek/mt76/mt792x_core.c
+++ b/drivers/net/wireless/mediatek/mt76/mt792x_core.c
@@ -358,7 +358,7 @@ void mt792x_get_et_strings(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	if (sset != ETH_SS_STATS)
 		return;
 
-	memcpy(data, *mt792x_gstrings_stats, sizeof(mt792x_gstrings_stats));
+	memcpy(data, mt792x_gstrings_stats, sizeof(mt792x_gstrings_stats));
 
 	data += sizeof(mt792x_gstrings_stats);
 	page_pool_ethtool_stats_get_strings(data);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/main.c b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
index c3a479dc3f53..2405ec1a663f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
@@ -1192,7 +1192,7 @@ void mt7996_get_et_strings(struct ieee80211_hw *hw,
 			   u32 sset, u8 *data)
 {
 	if (sset == ETH_SS_STATS)
-		memcpy(data, *mt7996_gstrings_stats,
+		memcpy(data, mt7996_gstrings_stats,
 		       sizeof(mt7996_gstrings_stats));
 }
 
-- 
2.41.0