diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-02-27 18:35:35 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 13:22:27 +0100 |
| commit | a83e4448958bd0542012648411b868c5a4d57b33 (patch) | |
| tree | f5ce62d9b35328bdc9608e084ded879a76b38b20 | |
| parent | 83d2de946101424e79335d0d72c9288344704065 (diff) | |
macvtap: make sure neighbour code can push ethernet header
[ Upstream commit 2f1d8b9e8afa5a833d96afcd23abcb8cdf8d83ab ]
Brian reported crashes using IPv6 traffic with macvtap/veth combo.
I tracked the crashes in neigh_hh_output()
-> memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
Neighbour code assumes headroom to push Ethernet header is
at least 16 bytes.
It appears macvtap has only 14 bytes available on arches
where NET_IP_ALIGN is 0 (like x86)
Effect is a corruption of 2 bytes right before skb->head,
and possible crashes if accessing non existing memory.
This fix should also increase IPv4 performance, as paranoid code
in ip_finish_output2() wont have to call skb_realloc_headroom()
Reported-by: Brian Rak <brak@vultr.com>
Tested-by: Brian Rak <brak@vultr.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/macvtap.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 2d255ba911d5..8fc46fcaee54 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -658,12 +658,15 @@ static unsigned long iov_pages(const struct iovec *iv, int offset, return pages; } +/* Neighbour code has some assumptions on HH_DATA_MOD alignment */ +#define MACVTAP_RESERVE HH_DATA_OFF(ETH_HLEN) + /* Get packet from user space buffer */ 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); + int good_linear = SKB_MAX_HEAD(MACVTAP_RESERVE); struct sk_buff *skb; struct macvlan_dev *vlan; unsigned long len = total_len; @@ -722,7 +725,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, linear = vnet_hdr.hdr_len; } - skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen, + skb = macvtap_alloc_skb(&q->sk, MACVTAP_RESERVE, copylen, linear, noblock, &err); if (!skb) goto err; |