From 2eb783c43e7cf807a45899c10ed556b6dc116625 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 3 Nov 2014 04:30:14 +0800 Subject: [PATCH] tun: Fix TUN_PKT_STRIP setting We set the flag TUN_PKT_STRIP if the user buffer provided is too small to contain the entire packet plus meta-data. However, this has been broken ever since we added GSO meta-data. VLAN acceleration also has the same problem. This patch fixes this by taking both into account when setting the TUN_PKT_STRIP flag. The fact that this has been broken for six years without anyone realising means that nobody actually uses this flag. Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr") Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- drivers/net/tun.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 57e6bf75a632..9dd3746994a4 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1236,15 +1236,19 @@ static ssize_t tun_put_user(struct tun_struct *tun, ssize_t total = 0; int vlan_offset = 0, copied; int vlan_hlen = 0; + int vnet_hdr_sz = 0; if (vlan_tx_tag_present(skb)) vlan_hlen = VLAN_HLEN; + if (tun->flags & TUN_VNET_HDR) + vnet_hdr_sz = tun->vnet_hdr_sz; + if (!(tun->flags & TUN_NO_PI)) { if ((len -= sizeof(pi)) < 0) return -EINVAL; - if (len < skb->len) { + if (len < skb->len + vlan_hlen + vnet_hdr_sz) { /* Packet will be striped */ pi.flags |= TUN_PKT_STRIP; } @@ -1254,9 +1258,9 @@ static ssize_t tun_put_user(struct tun_struct *tun, total += sizeof(pi); } - if (tun->flags & TUN_VNET_HDR) { + if (vnet_hdr_sz) { struct virtio_net_hdr gso = { 0 }; /* no info leak */ - if ((len -= tun->vnet_hdr_sz) < 0) + if ((len -= vnet_hdr_sz) < 0) return -EINVAL; if (skb_is_gso(skb)) { @@ -1298,7 +1302,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total, sizeof(gso)))) return -EFAULT; - total += tun->vnet_hdr_sz; + total += vnet_hdr_sz; } copied = total; -- 2.34.1