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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.14 151/151] dsa: tag_dsa: Fix mask for trunked packets
Date:   Mon, 11 Oct 2021 15:47:03 +0200
Message-Id: <20211011134522.723553019@linuxfoundation.org>
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From: Andrew Lunn <andrew@lunn.ch>

commit b44d52a50bc6f191f0ae03f65de8401f3ef039b3 upstream.

A packet received on a trunk will have bit 2 set in Forward DSA tagged
frame. Bit 1 can be either 0 or 1 and is otherwise undefined and bit 0
indicates the frame CFI. Masking with 7 thus results in frames as
being identified as being from a trunk when in fact they are not. Fix
the mask to just look at bit 2.

Fixes: 5b60dadb71db ("net: dsa: tag_dsa: Support reception of packets from LAG devices")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/dsa/tag_dsa.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/dsa/tag_dsa.c
+++ b/net/dsa/tag_dsa.c
@@ -176,7 +176,7 @@ static struct sk_buff *dsa_rcv_ll(struct
 	case DSA_CMD_FORWARD:
 		skb->offload_fwd_mark = 1;
 
-		trunk = !!(dsa_header[1] & 7);
+		trunk = !!(dsa_header[1] & 4);
 		break;
 
 	case DSA_CMD_TO_CPU: