3.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Julian Anastasov <[email protected]> [ Upstream commit 2c51a97f76d20ebf1f50fef908b986cb051fdff9 ] The lockless lookups can return entry that is unlinked. Sometimes they get reference before last neigh_cleanup_and_release, sometimes they do not need reference. Later, any modification attempts may result in the following problems: 1. entry is not destroyed immediately because neigh_update can start the timer for dead entry, eg. on change to NUD_REACHABLE state. As result, entry lives for some time but is invisible and out of control. 2. __neigh_event_send can run in parallel with neigh_destroy while refcnt=0 but if timer is started and expired refcnt can reach 0 for second time leading to second neigh_destroy and possible crash. Thanks to Eric Dumazet and Ying Xue for their work and analyze on the __neigh_event_send change. Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour") Fixes: a263b3093641 ("ipv4: Make neigh lookups directly in output packet path.") Fixes: 6fd6ce2056de ("ipv6: Do not depend on rt->n in ip6_finish_output2().") Cc: Eric Dumazet <[email protected]> Cc: Ying Xue <[email protected]> Signed-off-by: Julian Anastasov <[email protected]> Acked-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/core/neighbour.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -976,6 +976,8 @@ int __neigh_event_send(struct neighbour rc = 0; if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE)) goto out_unlock_bh; + if (neigh->dead) + goto out_dead; if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) { if (NEIGH_VAR(neigh->parms, MCAST_PROBES) + @@ -1032,6 +1034,13 @@ out_unlock_bh: write_unlock(&neigh->lock); local_bh_enable(); return rc; + +out_dead: + if (neigh->nud_state & NUD_STALE) + goto out_unlock_bh; + write_unlock_bh(&neigh->lock); + kfree_skb(skb); + return 1; } EXPORT_SYMBOL(__neigh_event_send); @@ -1095,6 +1104,8 @@ int neigh_update(struct neighbour *neigh if (!(flags & NEIGH_UPDATE_F_ADMIN) && (old & (NUD_NOARP | NUD_PERMANENT))) goto out; + if (neigh->dead) + goto out; if (!(new & NUD_VALID)) { neigh_del_timer(neigh); @@ -1244,6 +1255,8 @@ EXPORT_SYMBOL(neigh_update); */ void __neigh_set_probe_once(struct neighbour *neigh) { + if (neigh->dead) + return; neigh->updated = jiffies; if (!(neigh->nud_state & NUD_FAILED)) return; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
