[ 47/66] net: fix secpath kmemleak

[Greg Kroah-Hartman]

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 3d861f661006606bf159fd6bd973e83dbf21d0f9 ]

Mike Kazantsev found 3.5 kernels and beyond were leaking memory,
and tracked the faulty commit to a1c7fff7e18f59e ("net:
netdev_alloc_skb() use build_skb()")

While this commit seems fine, it uncovered a bug introduced
in commit bad43ca8325 ("net: introduce skb_try_coalesce()), in function
kfree_skb_partial()"):

If head is stolen, we free the sk_buff,
without removing references on secpath (skb->sp).

So IPsec + IP defrag/reassembly (using skb coalescing), or
TCP coalescing could leak secpath objects.

Fix this bug by calling skb_release_head_state(skb) to properly
release all possible references to linked objects.

Reported-by: Mike Kazantsev <mk.fraggod@xxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Bisected-by: Mike Kazantsev <mk.fraggod@xxxxxxxxx>
Tested-by: Mike Kazantsev <mk.fraggod@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/skbuff.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3384,10 +3384,12 @@ EXPORT_SYMBOL(__skb_warn_lro_forwarding)
 
 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen)
 {
-	if (head_stolen)
+	if (head_stolen) {
+		skb_release_head_state(skb);
 		kmem_cache_free(skbuff_head_cache, skb);
-	else
+	} else {
 		__kfree_skb(skb);
+	}
 }
 EXPORT_SYMBOL(kfree_skb_partial);
 


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