From 95556a883834122c616bbeb942654d745ceb9712 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 8 Jul 2016 11:03:57 +0200 Subject: [PATCH] dccp: avoid deadlock in dccp_v4_ctl_send_reset In the prep work I did before enabling BH while handling socket backlog, I missed two points in DCCP : 1) dccp_v4_ctl_send_reset() uses bh_lock_sock(), assuming BH were blocked. It is not anymore always true. 2) dccp_v4_route_skb() was using __IP_INC_STATS() instead of IP_INC_STATS() A similar fix was done for TCP, in commit 47dcc20a39d0 ("ipv4: tcp: ip_send_unicast_reply() is not BH safe") Fixes: 7309f8821fd6 ("dccp: do not assume DCCP code is non preemptible") Fixes: 5413d1babe8f ("net: do not block BH while processing socket backlog") Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Signed-off-by: David S. Miller --- net/dccp/ipv4.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 5c7e413a3ae4..25dd25b47d41 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -462,7 +462,7 @@ static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk, security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); rt = ip_route_output_flow(net, &fl4, sk); if (IS_ERR(rt)) { - __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); + IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); return NULL; } @@ -527,17 +527,19 @@ static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb) rxiph->daddr); skb_dst_set(skb, dst_clone(dst)); + local_bh_disable(); bh_lock_sock(ctl_sk); err = ip_build_and_send_pkt(skb, ctl_sk, rxiph->daddr, rxiph->saddr, NULL); bh_unlock_sock(ctl_sk); if (net_xmit_eval(err) == 0) { - DCCP_INC_STATS(DCCP_MIB_OUTSEGS); - DCCP_INC_STATS(DCCP_MIB_OUTRSTS); + __DCCP_INC_STATS(DCCP_MIB_OUTSEGS); + __DCCP_INC_STATS(DCCP_MIB_OUTRSTS); } + local_bh_enable(); out: - dst_release(dst); + dst_release(dst); } static void dccp_v4_reqsk_destructor(struct request_sock *req)