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From:   Haiyang Zhang <haiyangz@linuxonhyperv.com>
To:     davem@davemloft.net, netdev@vger.kernel.org
Cc:     haiyangz@microsoft.com, kys@microsoft.com, sthemmin@microsoft.com,
        olaf@aepfle.de, vkuznets@redhat.com, devel@linuxdriverproject.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH net-next] hv_netvsc: Fix rndis_per_packet_info internal field initialization
Date:   Fri, 28 Sep 2018 14:41:23 +0000
Message-Id: <20180928144123.11926-1-haiyangz@linuxonhyperv.com>
Reply-To: haiyangz@microsoft.com
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Haiyang Zhang <haiyangz@microsoft.com>

The RSC feature -- a bit field "internal" was added here with total
size unchanged:
struct rndis_per_packet_info {
	u32 size;
	u32 type:31;
	u32 internal:1;
	u32 ppi_offset;
};

On TX path, we put rndis msg into skb head room, which is not zeroed
before passing to us. We do not use the "internal" field in TX path,
but it may impact older hosts which use the entire 32 bits as "type".

To fix the bug, this patch sets the field "internal" to zero.

Fixes: c8e4eff4675f ("hv_netvsc: Add support for LRO/RSC in the vSwitch")
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 drivers/net/hyperv/netvsc_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index ec699741170b..005cbaa2fa3b 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -226,6 +226,7 @@ static inline void *init_ppi_data(struct rndis_message *msg,
 
 	ppi->size = ppi_size;
 	ppi->type = pkt_type;
+	ppi->internal = 0;
 	ppi->ppi_offset = sizeof(struct rndis_per_packet_info);
 
 	rndis_pkt->per_pkt_info_len += ppi_size;
-- 
2.18.0