commit 248e23b50e2da0753f3b5faa068939cbe9f8a75a upstream.
The function batadv_frag_skb_buffer was supposed not to consume the skbuff
on errors. This was followed in the helper function
batadv_frag_insert_packet when the skb would potentially be inserted in the
fragment queue. But it could happen that the next helper function
batadv_frag_merge_packets would try to merge the fragments and fail. This
results in a kfree_skb of all the enqueued fragments (including the just
inserted one). batadv_recv_frag_packet would detect the error in
batadv_frag_skb_buffer and try to free the skb again.
The behavior of batadv_frag_skb_buffer (and its helper
batadv_frag_insert_packet) must therefore be changed to always consume the
skbuff to have a common behavior and avoid the double kfree_skb.
Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
---
net/batman-adv/fragmentation.c | 8 +++++---
net/batman-adv/routing.c | 6 ++++++
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index a06b6041f3e0..384a1014da07 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -232,8 +232,10 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
spin_unlock_bh(&chain->lock);
err:
- if (!ret)
+ if (!ret) {
kfree(frag_entry_new);
+ kfree_skb(skb);
+ }
return ret;
}
@@ -305,7 +307,7 @@ batadv_frag_merge_packets(struct hlist_head *chain)
*
* There are three possible outcomes: 1) Packet is merged: Return true and
* set *skb to merged packet; 2) Packet is buffered: Return true and set *skb
- * to NULL; 3) Error: Return false and leave skb as is.
+ * to NULL; 3) Error: Return false and free skb.
*
* Return: true when packet is merged or buffered, false when skb is not not
* used.
@@ -330,9 +332,9 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb,
goto out_err;
out:
- *skb = skb_out;
ret = true;
out_err:
+ *skb = skb_out;
return ret;
}
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 8b98609ebc1e..f9ffb1825f6d 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1080,6 +1080,12 @@ int batadv_recv_frag_packet(struct sk_buff *skb,
batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_RX);
batadv_add_counter(bat_priv, BATADV_CNT_FRAG_RX_BYTES, skb->len);
+ /* batadv_frag_skb_buffer will always consume the skb and
+ * the caller should therefore never try to free the
+ * skb after this point
+ */
+ ret = NET_RX_SUCCESS;
+
/* Add fragment to buffer and merge if possible. */
if (!batadv_frag_skb_buffer(&skb, orig_node_src))
goto out;
--
2.20.1
