Commit 22cfb0bf authored Aug 16, 2011 by Bernd Schubert Committed by Roland Dreier Aug 16, 2011

IPoIB: Fix possible NULL dereference in ipoib_start_xmit()

Fix a bug introduced in 69cce1d1 ("net: Abstract dst->neighbour
accesses behind helpers.") where we might dereference skb_dst(skb)
even if it is NULL, which causes:

    [  240.944030] BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
    [  240.948007] IP: [<ffffffffa0366ce9>] ipoib_start_xmit+0x39/0x280 [ib_ipoib]
    [...]
    [  240.948007] Call Trace:
    [  240.948007]  <IRQ>
    [  240.948007]  [<ffffffff812cd5e0>] dev_hard_start_xmit+0x2a0/0x590
    [  240.948007]  [<ffffffff8131f680>] ? arp_create+0x70/0x200
    [  240.948007]  [<ffffffff812e8e1f>] sch_direct_xmit+0xef/0x1c0

Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=41212


Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: Roland Dreier <roland@purestorage.com>

parent 322a8b03

drivers/infiniband/ulp/ipoib/ipoib_main.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -717,11 +717,13 @@ static int ipoib_start_xmit(struct sk_buff skb, struct net_device dev)
		{
		struct ipoib_dev_priv *priv = netdev_priv(dev);
		struct ipoib_neigh *neigh;
		struct neighbour *n;
		struct neighbour *n = NULL;
		unsigned long flags;

		if (likely(skb_dst(skb)))
		n = dst_get_neighbour(skb_dst(skb));
		if (likely(skb_dst(skb) && n)) {

		if (likely(n)) {
		if (unlikely(!*to_ipoib_neigh(n))) {
		ipoib_path_lookup(skb, dev);
		return NETDEV_TX_OK;