* [B.A.T.M.A.N.] [PATCH] batman-adv: fix NULL pointer deref in batadv_find_best_neighbor
@ 2013-12-17 15:35 Simon Wunderlich
2013-12-25 14:15 ` Marek Lindner
0 siblings, 1 reply; 2+ messages in thread
From: Simon Wunderlich @ 2013-12-17 15:35 UTC (permalink / raw)
To: b.a.t.m.a.n
If there is no best neighbor, don't dereference the NULL pointer.
Introduced by 9bb33b8d88e318c4879d37d06ad28e3e018b9036 ("batman-adv:
split tq information in neigh_node struct")
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
originator.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/originator.c b/originator.c
index 2243003..9fcde58 100644
--- a/originator.c
+++ b/originator.c
@@ -789,7 +789,7 @@ batadv_find_best_neighbor(struct batadv_priv *bat_priv,
best, if_outgoing) <= 0))
best = neigh;
- if (!atomic_inc_not_zero(&best->refcount))
+ if (best && !atomic_inc_not_zero(&best->refcount))
best = NULL;
rcu_read_unlock();
--
1.7.10.4
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [B.A.T.M.A.N.] [PATCH] batman-adv: fix NULL pointer deref in batadv_find_best_neighbor
2013-12-17 15:35 [B.A.T.M.A.N.] [PATCH] batman-adv: fix NULL pointer deref in batadv_find_best_neighbor Simon Wunderlich
@ 2013-12-25 14:15 ` Marek Lindner
0 siblings, 0 replies; 2+ messages in thread
From: Marek Lindner @ 2013-12-25 14:15 UTC (permalink / raw)
To: The list for a Better Approach To Mobile Ad-hoc Networking
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On Tuesday 17 December 2013 16:35:13 Simon Wunderlich wrote:
> If there is no best neighbor, don't dereference the NULL pointer.
>
> Introduced by 9bb33b8d88e318c4879d37d06ad28e3e018b9036 ("batman-adv:
> split tq information in neigh_node struct")
>
> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
> ---
> originator.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/originator.c b/originator.c
> index 2243003..9fcde58 100644
> --- a/originator.c
> +++ b/originator.c
> @@ -789,7 +789,7 @@ batadv_find_best_neighbor(struct batadv_priv *bat_priv,
> best, if_outgoing) <= 0))
> best = neigh;
>
> - if (!atomic_inc_not_zero(&best->refcount))
> + if (best && !atomic_inc_not_zero(&best->refcount))
> best = NULL;
> rcu_read_unlock();
Although this is a valid fix the approach could be improved. The for-loop
should check whether the counter can be increased. Otherwise we might select a
best-neighbor that is being purged and end up with no best despite having
alternatives.
Cheers,
Marek
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2013-12-17 15:35 [B.A.T.M.A.N.] [PATCH] batman-adv: fix NULL pointer deref in batadv_find_best_neighbor Simon Wunderlich
2013-12-25 14:15 ` Marek Lindner
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