net: fix secpath kmemleak

[ 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@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Bisected-by: Mike Kazantsev <mk.fraggod@gmail.com>
Tested-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ef172afd3a8b4392508d4e04c4c2fb3051403fdc..97087775b1b350ad921a18630ebfd8c9d33bc6e6 100644 (file)
--- 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);