diff options
| author | Julian Anastasov <ja@ssi.bg> | 2015-06-16 22:56:39 +0300 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2019-05-02 14:30:26 +0200 |
| commit | 30a6caf5e2ec75b9e23e8f1be3c76be819e1b371 (patch) | |
| tree | cc48fefb325b417fe98d749368fa7508a3a8e41b /net/core | |
| parent | 9411ce1e9c402b34d66877dead2dd9e1e0510620 (diff) | |
neigh: do not modify unlinked entries
commit 2c51a97f76d20ebf1f50fef908b986cb051fdff9 upstream.
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().")
Change-Id: I09181080d56c2e343603412bc7ad390eee87be8f
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: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/neighbour.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 6e0c23fdd..a3e8daec6 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -973,6 +973,8 @@ 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->parms->mcast_probes + neigh->parms->app_probes) { @@ -1026,6 +1028,13 @@ 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); @@ -1089,6 +1098,8 @@ 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); |