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authorJulian Anastasov <ja@ssi.bg>2015-06-16 22:56:39 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-07-10 09:49:29 -0700
commit914b0ef228c97dfea025091428f6c7809c9d38ad (patch)
tree585a5392ffdca0d1f97ab05ecb8f605cbe01d569 /net
parent2c330edb4b31fdf18c6a6c4d1d9b482632c3925b (diff)
neigh: do not modify unlinked entries
[ 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 <eric.dumazet@gmail.com> Cc: Ying Xue <ying.xue@windriver.com> Signed-off-by: Julian Anastasov <ja@ssi.bg> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/neighbour.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 3de654256028..2237c1b3cdd2 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -957,6 +957,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
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) +
@@ -1013,6 +1015,13 @@ 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);
@@ -1076,6 +1085,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
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);
@@ -1225,6 +1236,8 @@ 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;