diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-02-27 18:35:35 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-02-28 23:57:19 -0500 |
| commit | 2f1d8b9e8afa5a833d96afcd23abcb8cdf8d83ab (patch) | |
| tree | 12dbce95e244af612094c4cc7aa8e7ed0ab46755 /drivers/net/macvtap.c | |
| parent | 32034e0580a9cd8cebd303ced20f54c06cb24f4d (diff) | |
| download | linux-2f1d8b9e8afa5a833d96afcd23abcb8cdf8d83ab.tar.gz | |
macvtap: make sure neighbour code can push ethernet header
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>
Diffstat (limited to 'drivers/net/macvtap.c')
| -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 e40fdfccc9c1..27ecc5c4fa26 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -654,11 +654,14 @@ static void macvtap_skb_to_vnet_hdr(struct macvtap_queue *q, } /* else everything is zero */ } +/* 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, struct iov_iter *from, 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 total_len = iov_iter_count(from); @@ -722,7 +725,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, linear = macvtap16_to_cpu(q, 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; |