From: Sven Eckelmann <sven@xxxxxxxxxxxxx>
The router is put down twice when it was non-NULL and either orig_ifinfo is
NULL afterwards or batman-adv receives a packet with the same sequence
number. This will end up in a use-after-free when the batadv_neigh_node is
removed because the reference counter ended up too early at 0.
Fixes: 9323158ef9f4 ("batman-adv: OGMv2 - implement originators logic")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Antonio Quartulli <a@xxxxxxxxxxx>
---
This patch is skipping netdev and is being sent directly to stable in
accordance with David S. Miller[1].
The reason is that this patch applies only on linux-4.6 and not on
linux-4.7/net because it was "accidentally" fixed by a refactoring
commit (more details in [2]).
It addresses a reference imbalance which systematically leads to a
use-after-free and then a kernel crash.
Cheers,
[1] https://www.mail-archive.com/b.a.t.m.a.n@xxxxxxxxxxxxxxxxxxx/msg15258.html
[2] https://www.mail-archive.com/b.a.t.m.a.n@xxxxxxxxxxxxxxxxxxx/msg15252.html
net/batman-adv/bat_v_ogm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c
index d9bcbe6e7d65..91df28a100f9 100644
--- a/net/batman-adv/bat_v_ogm.c
+++ b/net/batman-adv/bat_v_ogm.c
@@ -529,8 +529,10 @@ static void batadv_v_ogm_route_update(struct batadv_priv *bat_priv,
goto out;
}
- if (router)
+ if (router) {
batadv_neigh_node_put(router);
+ router = NULL;
+ }
/* Update routes, and check if the OGM is from the best next hop */
batadv_v_ogm_orig_update(bat_priv, orig_node, neigh_node, ogm2,
--
2.8.3
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