[linux-next] LinuxNextTracking branch, master, updated. next-20170306

batman at open-mesh.org batman at open-mesh.org
Tue Mar 7 00:15:54 CET 2017


The following commit has been merged in the master branch:
commit 248e23b50e2da0753f3b5faa068939cbe9f8a75a
Author: Sven Eckelmann <sven at 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 at narfation.org>
    Signed-off-by: Simon Wunderlich <sw at 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;
 }
 

-- 
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