From: Holger Eitzenberger Date: Mon, 27 Jan 2014 09:33:18 +0000 (+0100) Subject: net: Fix memory leak if TPROXY used with TCP early demux X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a452ce345d63ddf92cd101e4196569f8718ad319;p=linux-beck.git net: Fix memory leak if TPROXY used with TCP early demux I see a memory leak when using a transparent HTTP proxy using TPROXY together with TCP early demux and Kernel v3.8.13.15 (Ubuntu stable): unreferenced object 0xffff88008cba4a40 (size 1696): comm "softirq", pid 0, jiffies 4294944115 (age 8907.520s) hex dump (first 32 bytes): 0a e0 20 6a 40 04 1b 37 92 be 32 e2 e8 b4 00 00 .. j@..7..2..... 02 00 07 01 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] kmem_cache_alloc+0xad/0xb9 [] sk_prot_alloc+0x29/0xc5 [] sk_clone_lock+0x14/0x283 [] inet_csk_clone_lock+0xf/0x7b [] netlink_broadcast+0x14/0x16 [] tcp_create_openreq_child+0x1b/0x4c3 [] tcp_v4_syn_recv_sock+0x38/0x25d [] tcp_check_req+0x25c/0x3d0 [] tcp_v4_do_rcv+0x287/0x40e [] ip_route_input_noref+0x843/0xa55 [] tcp_v4_rcv+0x4c9/0x725 [] ip_local_deliver_finish+0xe9/0x154 [] __netif_receive_skb+0x4b2/0x514 [] process_backlog+0xee/0x1c5 [] net_rx_action+0xa7/0x200 [] add_interrupt_randomness+0x39/0x157 But there are many more, resulting in the machine going OOM after some days. From looking at the TPROXY code, and with help from Florian, I see that the memory leak is introduced in tcp_v4_early_demux(): void tcp_v4_early_demux(struct sk_buff *skb) { /* ... */ iph = ip_hdr(skb); th = tcp_hdr(skb); if (th->doff < sizeof(struct tcphdr) / 4) return; sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo, iph->saddr, th->source, iph->daddr, ntohs(th->dest), skb->skb_iif); if (sk) { skb->sk = sk; where the socket is assigned unconditionally to skb->sk, also bumping the refcnt on it. This is problematic, because in our case the skb has already a socket assigned in the TPROXY target. This then results in the leak I see. The very same issue seems to be with IPv6, but haven't tested. Reviewed-by: Florian Westphal Signed-off-by: Holger Eitzenberger Signed-off-by: David S. Miller --- diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c index 054a3e97d822..3d4da2c16b6a 100644 --- a/net/ipv4/ip_input.c +++ b/net/ipv4/ip_input.c @@ -314,7 +314,7 @@ static int ip_rcv_finish(struct sk_buff *skb) const struct iphdr *iph = ip_hdr(skb); struct rtable *rt; - if (sysctl_ip_early_demux && !skb_dst(skb)) { + if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) { const struct net_protocol *ipprot; int protocol = iph->protocol; diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index 302d6fb1ff2b..51d54dc376f3 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -49,7 +49,7 @@ int ip6_rcv_finish(struct sk_buff *skb) { - if (sysctl_ip_early_demux && !skb_dst(skb)) { + if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) { const struct inet6_protocol *ipprot; ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);