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authorEric Dumazet <edumazet@google.com>2015-02-27 18:35:35 -0800
committerDavid S. Miller <davem@davemloft.net>2015-02-28 23:57:19 -0500
commit2f1d8b9e8afa5a833d96afcd23abcb8cdf8d83ab (patch)
tree12dbce95e244af612094c4cc7aa8e7ed0ab46755 /drivers/net
parent32034e0580a9cd8cebd303ced20f54c06cb24f4d (diff)
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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')
-rw-r--r--drivers/net/macvtap.c7
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;