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authorJason Wang <jasowang@redhat.com>2013-11-13 14:00:40 +0800
committerDavid S. Miller <davem@davemloft.net>2013-11-14 16:05:27 -0500
commit16a3fa28630331e28208872fa5341ce210b901c7 (patch)
tree2c87d8d0b55f26c9fcc723f2f7760a455a09d4da /drivers/net/macvtap.c
parent96f8d9ecf227638c89f98ccdcdd50b569891976c (diff)
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.c8
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,