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| author | Eric Dumazet <edumazet@google.com> | 2017-10-24 08:20:31 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-26 17:41:32 +0900 |
| commit | 06f877d613be3621604c2520ec0351d9fbdca15f (patch) | |
| tree | c7408afed6ebde2a04f1ee9bdd7932780f7e64fe /include | |
| parent | a0c0865fa0abcbc142c11fabec3a2bffc1a4229d (diff) | |
| download | linux-rpi-06f877d613be3621604c2520ec0351d9fbdca15f.tar.gz linux-rpi-06f877d613be3621604c2520ec0351d9fbdca15f.tar.bz2 linux-rpi-06f877d613be3621604c2520ec0351d9fbdca15f.zip | |
tcp/dccp: fix other lockdep splats accessing ireq_opt
In my first attempt to fix the lockdep splat, I forgot we could
enter inet_csk_route_req() with a freshly allocated request socket,
for which refcount has not yet been elevated, due to complex
SLAB_TYPESAFE_BY_RCU rules.
We either are in rcu_read_lock() section _or_ we own a refcount on the
request.
Correct RCU verb to use here is rcu_dereference_check(), although it is
not possible to prove we actually own a reference on a shared
refcount :/
In v2, I added ireq_opt_deref() helper and use in three places, to fix other
possible splats.
[ 49.844590] lockdep_rcu_suspicious+0xea/0xf3
[ 49.846487] inet_csk_route_req+0x53/0x14d
[ 49.848334] tcp_v4_route_req+0xe/0x10
[ 49.850174] tcp_conn_request+0x31c/0x6a0
[ 49.851992] ? __lock_acquire+0x614/0x822
[ 49.854015] tcp_v4_conn_request+0x5a/0x79
[ 49.855957] ? tcp_v4_conn_request+0x5a/0x79
[ 49.858052] tcp_rcv_state_process+0x98/0xdcc
[ 49.859990] ? sk_filter_trim_cap+0x2f6/0x307
[ 49.862085] tcp_v4_do_rcv+0xfc/0x145
[ 49.864055] ? tcp_v4_do_rcv+0xfc/0x145
[ 49.866173] tcp_v4_rcv+0x5ab/0xaf9
[ 49.868029] ip_local_deliver_finish+0x1af/0x2e7
[ 49.870064] ip_local_deliver+0x1b2/0x1c5
[ 49.871775] ? inet_del_offload+0x45/0x45
[ 49.873916] ip_rcv_finish+0x3f7/0x471
[ 49.875476] ip_rcv+0x3f1/0x42f
[ 49.876991] ? ip_local_deliver_finish+0x2e7/0x2e7
[ 49.878791] __netif_receive_skb_core+0x6d3/0x950
[ 49.880701] ? process_backlog+0x7e/0x216
[ 49.882589] __netif_receive_skb+0x1d/0x5e
[ 49.884122] process_backlog+0x10c/0x216
[ 49.885812] net_rx_action+0x147/0x3df
Fixes: a6ca7abe53633 ("tcp/dccp: fix lockdep splat in inet_csk_route_req()")
Fixes: c92e8c02fe66 ("tcp/dccp: fix ireq->opt races")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: kernel test robot <fengguang.wu@intel.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/inet_sock.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index 425752f768d2..db8162dd8c0b 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -132,6 +132,12 @@ static inline int inet_request_bound_dev_if(const struct sock *sk, return sk->sk_bound_dev_if; } +static inline struct ip_options_rcu *ireq_opt_deref(const struct inet_request_sock *ireq) +{ + return rcu_dereference_check(ireq->ireq_opt, + refcount_read(&ireq->req.rsk_refcnt) > 0); +} + struct inet_cork { unsigned int flags; __be32 addr; |