diff options
| author | Jason Wang <jasowang@redhat.com> | 2013-11-13 14:00:40 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2015-05-09 23:16:38 +0100 |
| commit | 75f9b4534aa31e33e96ae36dd96a62907470da91 (patch) | |
| tree | 0b299331b8bdae6d2aa63db69878e292092e0ea5 | |
| parent | d501ebeb7da7531e92e3c8d194730341c314ff2d (diff) | |
macvtap: limit head length of skb allocated
commit 16a3fa28630331e28208872fa5341ce210b901c7 upstream.
We currently use hdr_len as a hint of head length which is advertised by
guest. But when guest advertise a very big value, it can lead to an 64K+
allocating of kmalloc() which has a very high possibility of failure when host
memory is fragmented or under heavy stress. The huge hdr_len also reduce the
effect of zerocopy or even disable if a gso skb is linearized in guest.
To solves those issues, this patch introduces an upper limit (PAGE_SIZE) of the
head, which guarantees an order 0 allocation each time.
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/net/macvtap.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 0e6e57ed1a2f..07ca8d3add18 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -672,6 +672,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, const struct iovec *iv, unsigned long total_len, size_t count, int noblock) { + int good_linear = SKB_MAX_HEAD(NET_IP_ALIGN); struct sk_buff *skb; struct macvlan_dev *vlan; unsigned long len = total_len; @@ -714,6 +715,8 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { copylen = vnet_hdr.hdr_len ? vnet_hdr.hdr_len : GOODCOPY_LEN; + if (copylen > good_linear) + copylen = good_linear; linear = copylen; if (iov_pages(iv, vnet_hdr_len + copylen, count) <= MAX_SKB_FRAGS) @@ -722,7 +725,10 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, if (!zerocopy) { copylen = len; - linear = vnet_hdr.hdr_len; + if (vnet_hdr.hdr_len > good_linear) + linear = good_linear; + else + linear = vnet_hdr.hdr_len; } skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen, |