From: Jason Wang <jasowang@redhat.com>
To: davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>
Subject: [PATCH net 1/2] tuntap: correctly linearize skb when zerocopy is used
Date: Tue, 9 Jul 2013 18:10:50 +0800 [thread overview]
Message-ID: <1373364651-10474-1-git-send-email-jasowang@redhat.com> (raw)
Userspace may produce vectors greater than MAX_SKB_FRAGS. When we try to
linearize parts of the skb to let the rest of iov to be fit in
the frags, we need count copylen into linear when calling tun_alloc_skb()
instead of partly counting it into data_len. Since this breaks
zerocopy_sg_from_iovec() since its inner counter assumes nr_frags should
be zero at beginning. This cause nr_frags to be increased wrongly without
setting the correct frags.
This bug were introduced from 0690899b4d4501b3505be069b9a687e68ccbe15b
(tun: experimental zero copy tx support)
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
This patch is needed for stable.
---
drivers/net/tun.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7eab5fc..01d5a86 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1109,7 +1109,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
} else
copylen = len;
- skb = tun_alloc_skb(tfile, align, copylen, gso.hdr_len, noblock);
+ skb = tun_alloc_skb(tfile, align, copylen,
+ zerocopy ? copylen : gso.hdr_len, noblock);
if (IS_ERR(skb)) {
if (PTR_ERR(skb) != -EAGAIN)
tun->dev->stats.rx_dropped++;
--
1.7.1
next reply other threads:[~2013-07-09 10:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-09 10:10 Jason Wang [this message]
2013-07-09 10:10 ` [PATCH net 2/2] macvtap: correctly linearize skb when zerocopy is used Jason Wang
2013-07-09 10:35 ` Michael S. Tsirkin
2013-07-10 5:17 ` Jason Wang
2013-07-09 10:34 ` [PATCH net 1/2] tuntap: " Michael S. Tsirkin
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