netfilter: ctnetlink: fix loop in ctnetlink_get_conntrack() From: Pablo Neira Ayuso This patch fixes a loop in ctnetlink_get_conntrack() that can be triggered if you use the same socket to receive events and to perform a GET operation. Under heavy load, netlink_unicast() may return -EAGAIN, this error code is reserved in nfnetlink for the module load-on-demand. Instead, we return -ENOBUFS which is the appropriate error code that has to be propagated to user-space. Reported-by: Holger Eitzenberger Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_netlink.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index b729ace..a84fa6f 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -973,7 +973,8 @@ ctnetlink_get_conntrack(struct sock *ctnl, struct sk_buff *skb, free: kfree_skb(skb2); out: - return err; + /* this avoids a loop in nfnetlink. */ + return err == -EAGAIN ? -ENOBUFS : err; } #ifdef CONFIG_NF_NAT_NEEDED