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| author | Jason Wang <jasowang@redhat.com> | 2013-11-13 14:00:40 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-11-14 16:05:27 -0500 |
| commit | 16a3fa28630331e28208872fa5341ce210b901c7 (patch) | |
| tree | 2c87d8d0b55f26c9fcc723f2f7760a455a09d4da /drivers/net/macvtap.c | |
| parent | 96f8d9ecf227638c89f98ccdcdd50b569891976c (diff) | |
| download | linux-16a3fa28630331e28208872fa5341ce210b901c7.tar.bz2 | |
macvtap: limit head length of skb allocated
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>
Diffstat (limited to 'drivers/net/macvtap.c')
| -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 9dccb1edfd2a..dc76670c2f2a 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -628,6 +628,7 @@ 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; @@ -670,6 +671,8 @@ 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) @@ -678,7 +681,10 @@ 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, |