4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet <edumazet@xxxxxxxxxx> [ Upstream commit 48481c8fa16410ffa45939b13b6c53c2ca609e5f ] Dmitry posted a nice reproducer of a bug triggering in neigh_probe() when dereferencing a NULL neigh->ops->solicit method. This can happen for arp_direct_ops/ndisc_direct_ops and similar, which can be used for NUD_NOARP neighbours (created when dev->header_ops is NULL). Admin can then force changing nud_state to some other state that would fire neigh timer. Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/core/neighbour.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -860,7 +860,8 @@ static void neigh_probe(struct neighbour if (skb) skb = skb_clone(skb, GFP_ATOMIC); write_unlock(&neigh->lock); - neigh->ops->solicit(neigh, skb); + if (neigh->ops->solicit) + neigh->ops->solicit(neigh, skb); atomic_inc(&neigh->probes); kfree_skb(skb); }