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From:   Jeremy Kerr <jk@ozlabs.org>
To:     netdev@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Finn Thain <fthain@telegraphics.com.au>,
        Stan Johnson <userm57@yahoo.com>
Subject: [PATCH] net: bmac: Fix read of MAC address from ROM
Date:   Tue, 19 May 2020 09:05:58 +0800
Message-Id: <20200519010558.24805-1-jk@ozlabs.org>
In-Reply-To: <4863b7d34cf23d269921ad133dc585ec83a0bb63.camel@ozlabs.org>
References: <4863b7d34cf23d269921ad133dc585ec83a0bb63.camel@ozlabs.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In bmac_get_station_address, We're reading two bytes at a time from ROM,
but we do that six times, resulting in 12 bytes of read & writes. This
means we will write off the end of the six-byte destination buffer.

This change fixes the for-loop to only read/write six bytes.

Based on a proposed fix from Finn Thain <fthain@telegraphics.com.au>.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Reported-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Stan Johnson <userm57@yahoo.com>
Reported-by: Finn Thain <fthain@telegraphics.com.au>
---
 drivers/net/ethernet/apple/bmac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/apple/bmac.c b/drivers/net/ethernet/apple/bmac.c
index a58185b1d8bf..3e3711b60d01 100644
--- a/drivers/net/ethernet/apple/bmac.c
+++ b/drivers/net/ethernet/apple/bmac.c
@@ -1182,7 +1182,7 @@ bmac_get_station_address(struct net_device *dev, unsigned char *ea)
 	int i;
 	unsigned short data;
 
-	for (i = 0; i < 6; i++)
+	for (i = 0; i < 3; i++)
 		{
 			reset_and_select_srom(dev);
 			data = read_srom(dev, i + EnetAddressOffset/2, SROMAddressBits);
-- 
2.17.1