netdev - [PATCH net 6/6] net: dsa: ksz: fix wrong read cast to u64

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Date:   Wed, 13 Jan 2021 13:45:22 +0100
From:   Gilles DOFFE <gilles.doffe@...oirfairelinux.com>
To:     netdev@...r.kernel.org
Cc:     Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH net 6/6] net: dsa: ksz: fix wrong read cast to u64

'(u64)*value' casts a u32 to a u64. So depending on endianness,
LSB or MSB is lost.
The pointer needs to be cast to read the full u64:
'*((u64 *)value)'

Signed-off-by: Gilles DOFFE <gilles.doffe@...oirfairelinux.com>
---
 drivers/net/dsa/microchip/ksz_common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
index 44e97c55c2da..492dcb2011f1 100644
--- a/drivers/net/dsa/microchip/ksz_common.h
+++ b/drivers/net/dsa/microchip/ksz_common.h
@@ -213,7 +213,7 @@ static inline int ksz_read64(struct ksz_device *dev, u32 reg, u64 *val)
 		/* Ick! ToDo: Add 64bit R/W to regmap on 32bit systems */
 		value[0] = swab32(value[0]);
 		value[1] = swab32(value[1]);
-		*val = swab64((u64)*value);
+		*val = swab64((((u64)value[1]) << 32) | value[0]);
 	}
 
 	return ret;
-- 
2.25.1