linux-kernel - [PATCH 5.4 033/111] net: hsr: Reset MAC header for Tx path

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Message-Id: <20210412084005.357849001@linuxfoundation.org>
Date:   Mon, 12 Apr 2021 10:40:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kurt Kanzenbach <kurt@...utronix.de>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.4 033/111] net: hsr: Reset MAC header for Tx path

From: Kurt Kanzenbach <kurt@...utronix.de>

commit 9d6803921a16f4d768dc41a75375629828f4d91e upstream.

Reset MAC header in HSR Tx path. This is needed, because direct packet
transmission, e.g. by specifying PACKET_QDISC_BYPASS does not reset the MAC
header.

This has been observed using the following setup:

|$ ip link add name hsr0 type hsr slave1 lan0 slave2 lan1 supervision 45 version 1
|$ ifconfig hsr0 up
|$ ./test hsr0

The test binary is using mmap'ed sockets and is specifying the
PACKET_QDISC_BYPASS socket option.

This patch resolves the following warning on a non-patched kernel:

|[  112.725394] ------------[ cut here ]------------
|[  112.731418] WARNING: CPU: 1 PID: 257 at net/hsr/hsr_forward.c:560 hsr_forward_skb+0x484/0x568
|[  112.739962] net/hsr/hsr_forward.c:560: Malformed frame (port_src hsr0)

The warning can be safely removed, because the other call sites of
hsr_forward_skb() make sure that the skb is prepared correctly.

Fixes: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option")
Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/hsr/hsr_device.c  |    1 +
 net/hsr/hsr_forward.c |    6 ------
 2 files changed, 1 insertion(+), 6 deletions(-)

--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -229,6 +229,7 @@ static int hsr_dev_xmit(struct sk_buff *
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 	if (master) {
 		skb->dev = master->dev;
+		skb_reset_mac_header(skb);
 		hsr_forward_skb(skb, master);
 	} else {
 		atomic_long_inc(&dev->tx_dropped);
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -349,12 +349,6 @@ void hsr_forward_skb(struct sk_buff *skb
 {
 	struct hsr_frame_info frame;
 
-	if (skb_mac_header(skb) != skb->data) {
-		WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n",
-			  __FILE__, __LINE__, port->dev->name);
-		goto out_drop;
-	}
-
 	if (hsr_fill_frame_info(&frame, skb, port) < 0)
 		goto out_drop;
 	hsr_register_frame_in(frame.node_src, port, frame.sequence_nr);