From 1b8e6a01e19f001e9f93b39c32387961c91ed3cc Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 18 Nov 2015 12:40:13 -0800 Subject: [PATCH] tcp: md5: fix lockdep annotation When a passive TCP is created, we eventually call tcp_md5_do_add() with sk pointing to the child. It is not owner by the user yet (we will add this socket into listener accept queue a bit later anyway) But we do own the spinlock, so amend the lockdep annotation to avoid following splat : [ 8451.090932] net/ipv4/tcp_ipv4.c:923 suspicious rcu_dereference_protected() usage! [ 8451.090932] [ 8451.090932] other info that might help us debug this: [ 8451.090932] [ 8451.090934] [ 8451.090934] rcu_scheduler_active = 1, debug_locks = 1 [ 8451.090936] 3 locks held by socket_sockopt_/214795: [ 8451.090936] #0: (rcu_read_lock){.+.+..}, at: [] __netif_receive_skb_core+0x151/0xe90 [ 8451.090947] #1: (rcu_read_lock){.+.+..}, at: [] ip_local_deliver_finish+0x43/0x2b0 [ 8451.090952] #2: (slock-AF_INET){+.-...}, at: [] sk_clone_lock+0x1c5/0x500 [ 8451.090958] [ 8451.090958] stack backtrace: [ 8451.090960] CPU: 7 PID: 214795 Comm: socket_sockopt_ [ 8451.091215] Call Trace: [ 8451.091216] [] dump_stack+0x55/0x76 [ 8451.091229] [] lockdep_rcu_suspicious+0xeb/0x110 [ 8451.091235] [] tcp_md5_do_add+0x1bf/0x1e0 [ 8451.091239] [] tcp_v4_syn_recv_sock+0x1f1/0x4c0 [ 8451.091242] [] ? tcp_v4_md5_hash_skb+0x167/0x190 [ 8451.091246] [] tcp_check_req+0x3c8/0x500 [ 8451.091249] [] ? tcp_v4_inbound_md5_hash+0x11e/0x190 [ 8451.091253] [] tcp_v4_rcv+0x3c0/0x9f0 [ 8451.091256] [] ? ip_local_deliver_finish+0x43/0x2b0 [ 8451.091260] [] ip_local_deliver_finish+0xb6/0x2b0 [ 8451.091263] [] ? ip_local_deliver_finish+0x43/0x2b0 [ 8451.091267] [] ip_local_deliver+0x48/0x80 [ 8451.091270] [] ip_rcv_finish+0x160/0x700 [ 8451.091273] [] ip_rcv+0x29e/0x3d0 [ 8451.091277] [] __netif_receive_skb_core+0xb47/0xe90 Fixes: a8afca0329988 ("tcp: md5: protects md5sig_info with RCU") Signed-off-by: Eric Dumazet Reported-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index ba09016d1bfd..db003438aaf5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -921,7 +921,8 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, } md5sig = rcu_dereference_protected(tp->md5sig_info, - sock_owned_by_user(sk)); + sock_owned_by_user(sk) || + lockdep_is_held(&sk->sk_lock.slock)); if (!md5sig) { md5sig = kmalloc(sizeof(*md5sig), gfp); if (!md5sig) -- 2.34.1