linux-kernel - [PATCH 3.4 06/27] macvtap: signal truncated packets

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Message-Id: <20140114002623.541438650@linuxfoundation.org>
Date:	Mon, 13 Jan 2014 16:26:20 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Vlad Yasevich <vyasevich@...il.com>,
	Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.4 06/27] macvtap: signal truncated packets

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wang <jasowang@...hat.com>

[ Upstream commit ce232ce01d61b184202bb185103d119820e1260c ]

macvtap_put_user() never return a value grater than iov length, this in fact
bypasses the truncated checking in macvtap_recvmsg(). Fix this by always
returning the size of packet plus the possible vlan header to let the trunca
checking work.

Cc: Vlad Yasevich <vyasevich@...il.com>
Cc: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
Cc: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Jason Wang <jasowang@...hat.com>
Acked-by: Vlad Yasevich <vyasevich@...il.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/macvtap.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -800,7 +800,7 @@ static ssize_t macvtap_put_user(struct m
 	int ret;
 	int vnet_hdr_len = 0;
 	int vlan_offset = 0;
-	int copied;
+	int copied, total;
 
 	if (q->flags & IFF_VNET_HDR) {
 		struct virtio_net_hdr vnet_hdr;
@@ -815,7 +815,8 @@ static ssize_t macvtap_put_user(struct m
 		if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr)))
 			return -EFAULT;
 	}
-	copied = vnet_hdr_len;
+	total = copied = vnet_hdr_len;
+	total += skb->len;
 
 	if (!vlan_tx_tag_present(skb))
 		len = min_t(int, skb->len, len);
@@ -830,6 +831,7 @@ static ssize_t macvtap_put_user(struct m
 
 		vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
 		len = min_t(int, skb->len + VLAN_HLEN, len);
+		total += VLAN_HLEN;
 
 		copy = min_t(int, vlan_offset, len);
 		ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
@@ -847,10 +849,9 @@ static ssize_t macvtap_put_user(struct m
 	}
 
 	ret = skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
-	copied += len;
 
 done:
-	return ret ? ret : copied;
+	return ret ? ret : total;
 }
 
 static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
@@ -904,7 +905,7 @@ static ssize_t macvtap_aio_read(struct k
 	}
 
 	ret = macvtap_do_read(q, iocb, iv, len, file->f_flags & O_NONBLOCK);
-	ret = min_t(ssize_t, ret, len); /* XXX copied from tun.c. Why? */
+	ret = min_t(ssize_t, ret, len);
 	if (ret > 0)
 		iocb->ki_pos = ret;
 out:


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