On Tue, 2012-03-06 at 12:22 +0100, pablo@xxxxxxxxxxxxx wrote:
> From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
>
> All ctnetlink operations are invoked inside rcu_read_lock
> (see net/netfilter/nfnetlink.c).
>
> Allocations have to be atomic, as RCU requires.
>
> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> ---
> net/netfilter/nf_conntrack_netlink.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index 1068769..867843f 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -1002,7 +1002,7 @@ ctnetlink_get_conntrack(struct sock *ctnl, struct sk_buff *skb,
> ct = nf_ct_tuplehash_to_ctrack(h);
>
> err = -ENOMEM;
> - skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
> if (skb2 == NULL) {
> nf_ct_put(ct);
> return -ENOMEM;
> @@ -1865,7 +1865,7 @@ ctnetlink_get_expect(struct sock *ctnl, struct sk_buff *skb,
> }
>
> err = -ENOMEM;
> - skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> + skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
> if (skb2 == NULL) {
> nf_ct_expect_put(exp);
> goto out;
This cant be right.
Really this must be kept as GFP_KERNEL allocations.
Only if .call_rcu member is used in place of .call rcu_read_lock() is
held instead of nfnl_lock().
You should take a look at all GFP_ATOMIC uses in
net/netfilter/nf_conntrack_netlink.c and check if they can be GFP_KERNEL
instead.
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