From: Sven Eckelmann <s...@narfation.org>
The receive function may start processing an incoming packet while the
hard_iface is shut down in a different context. All called functions called
with the batadv_hard_iface object belonging to the incoming interface would
have to check whether the reference counter is still > 0.
This is rather error-prone because this check can be forgotten easily.
Instead check the reference counter when receiving the object to make sure
that all called functions have a valid reference.
Signed-off-by: Sven Eckelmann <s...@narfation.org>
Signed-off-by: Marek Lindner <mareklind...@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a...@unstable.cc>
---
net/batman-adv/main.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 78c05a91ae6f..c8d8bc78a518 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -401,11 +401,19 @@ int batadv_batman_skb_recv(struct sk_buff *skb, struct
net_device *dev,
hard_iface = container_of(ptype, struct batadv_hard_iface,
batman_adv_ptype);
+
+ /* Prevent processing a packet received on an interface which is getting
+ * shut down otherwise the packet may trigger de-reference errors
+ * further down in the receive path.
+ */
+ if (!kref_get_unless_zero(&hard_iface->refcount))
+ goto err_out;
+
skb = skb_share_check(skb, GFP_ATOMIC);
/* skb was released by skb_share_check() */
if (!skb)
- goto err_out;
+ goto err_put;
/* packet should hold at least type and version */
if (unlikely(!pskb_may_pull(skb, 2)))
@@ -448,6 +456,8 @@ int batadv_batman_skb_recv(struct sk_buff *skb, struct
net_device *dev,
if (ret == NET_RX_DROP)
kfree_skb(skb);
+ batadv_hardif_put(hard_iface);
+
/* return NET_RX_SUCCESS in any case as we
* most probably dropped the packet for
* routing-logical reasons.
@@ -456,6 +466,8 @@ int batadv_batman_skb_recv(struct sk_buff *skb, struct
net_device *dev,
err_free:
kfree_skb(skb);
+err_put:
+ batadv_hardif_put(hard_iface);
err_out:
return NET_RX_DROP;
}
--
2.8.2
