From: Jason Wang <jasowang@redhat.com>
To: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH v2 net 2/2] macvtap: correctly linearize skb when zerocopy is used
Date: Wed, 10 Jul 2013 13:43:28 +0800 [thread overview]
Message-ID: <1373435008-19407-2-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1373435008-19407-1-git-send-email-jasowang@redhat.com>
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 macvtap_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 b92946e2919134ebe2a4083e4302236295ea2a73
(macvtap: zerocopy: validate vectors before building skb).
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
- This patch is needed for stable.
- Changes from v1: introduce a local variable to track linear size.
---
drivers/net/macvtap.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index b6dd6a7..502d948 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -647,6 +647,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
int vnet_hdr_len = 0;
int copylen = 0;
bool zerocopy = false;
+ size_t linear;
if (q->flags & IFF_VNET_HDR) {
vnet_hdr_len = q->vnet_hdr_sz;
@@ -701,11 +702,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
copylen = vnet_hdr.hdr_len;
if (!copylen)
copylen = GOODCOPY_LEN;
- } else
+ linear = copylen;
+ } else {
copylen = len;
+ linear = vnet_hdr.hdr_len;
+ }
skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen,
- vnet_hdr.hdr_len, noblock, &err);
+ linear, noblock, &err);
if (!skb)
goto err;
--
1.7.1
next prev parent reply other threads:[~2013-07-10 5:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-10 5:43 [PATCH v2 net 1/2] tuntap: correctly linearize skb when zerocopy is used Jason Wang
2013-07-10 5:43 ` Jason Wang [this message]
2013-07-10 6:15 ` [PATCH v2 net 2/2] macvtap: " Michael S. Tsirkin
2013-07-10 6:15 ` [PATCH v2 net 1/2] tuntap: " Michael S. Tsirkin
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