This is a note to let you know that I've just added the patch titled
neigh: do not modify unlinked entries
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
neigh-do-not-modify-unlinked-entries.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Jul 3 19:59:07 PDT 2015
From: Julian Anastasov <ja@xxxxxx>
Date: Tue, 16 Jun 2015 22:56:39 +0300
Subject: neigh: do not modify unlinked entries
From: Julian Anastasov <ja@xxxxxx>
[ 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@xxxxxxxxx>
Cc: Ying Xue <ying.xue@xxxxxxxxxxxxx>
Signed-off-by: Julian Anastasov <ja@xxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
Patches currently in stable-queue which might be from ja@xxxxxx are
queue-3.14/neigh-do-not-modify-unlinked-entries.patch
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