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@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de --- 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;