The following commit has been merged in the master branch: commit 248e23b50e2da0753f3b5faa068939cbe9f8a75a Author: Sven Eckelmann sven@narfation.org Date: Sun Feb 12 11:26:33 2017 +0100

batman-adv: Fix double free during fragment merge error

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

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index 0854ebd..31e97e9 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -239,8 +239,10 @@ err_unlock: spin_unlock_bh(&chain->lock);

err: - if (!ret) + if (!ret) { kfree(frag_entry_new); + kfree_skb(skb); + }

return ret; } @@ -313,7 +315,7 @@ free: * * 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. @@ -338,9 +340,9 @@ 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; }