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net: fix secpath kmemleak

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Mike Kazantsev found 3.5 kernels and beyond were leaking memory,
and tracked the faulty commit to a1c7fff7e1 ("net:
netdev_alloc_skb() use build_skb()")

While this commit seems fine, it uncovered a bug introduced
in commit bad43ca832 ("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>
This commit is contained in:
Eric Dumazet 2012-10-22 09:03:40 +00:00 committed by David S. Miller
parent 8a6e29d6d0
commit 3d861f6610
1 changed files with 4 additions and 2 deletions
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6
net/core/skbuff.c
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@ -3379,10 +3379,12 @@ 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);