diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-12-13 18:20:41 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-04 13:41:12 +0100 |
| commit | 792365bfcf3c753a792a4150314d24dd6a7721ea (patch) | |
| tree | 440802a82dc569809b5f3c69ec281719b7f37ecc /include/net | |
| parent | 0a8f421b7a224447ac4ebdef466ad6151023b33d (diff) | |
tcp/dccp: fix possible race __inet_lookup_established()
commit 8dbd76e79a16b45b2ccb01d2f2e08dbf64e71e40 upstream.
Michal Kubecek and Firo Yang did a very nice analysis of crashes
happening in __inet_lookup_established().
Since a TCP socket can go from TCP_ESTABLISH to TCP_LISTEN
(via a close()/socket()/listen() cycle) without a RCU grace period,
I should not have changed listeners linkage in their hash table.
They must use the nulls protocol (Documentation/RCU/rculist_nulls.txt),
so that a lookup can detect a socket in a hash list was moved in
another one.
Since we added code in commit d296ba60d8e2 ("soreuseport: Resolve
merge conflict for v4/v6 ordering fix"), we have to add
hlist_nulls_add_tail_rcu() helper.
Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Reported-by: Firo Yang <firo.yang@suse.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Link: https://lore.kernel.org/netdev/20191120083919.GH27852@unicorn.suse.cz/
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
[stable-4.9: we also need to update code in __inet_lookup_listener() and
inet6_lookup_listener() which has been removed in 5.0-rc1.]
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/inet_hashtables.h | 12 | ||||
| -rw-r--r-- | include/net/sock.h | 5 |
2 files changed, 14 insertions, 3 deletions
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h index 0574493e3899..fc445e7ccadf 100644 --- a/include/net/inet_hashtables.h +++ b/include/net/inet_hashtables.h @@ -98,12 +98,18 @@ struct inet_bind_hashbucket { struct hlist_head chain; }; -/* - * Sockets can be hashed in established or listening table +/* Sockets can be hashed in established or listening table. + * We must use different 'nulls' end-of-chain value for all hash buckets : + * A socket might transition from ESTABLISH to LISTEN state without + * RCU grace period. A lookup in ehash table needs to handle this case. */ +#define LISTENING_NULLS_BASE (1U << 29) struct inet_listen_hashbucket { spinlock_t lock; - struct hlist_head head; + union { + struct hlist_head head; + struct hlist_nulls_head nulls_head; + }; }; /* This is for listening sockets, thus all sockets which possess wildcards. */ diff --git a/include/net/sock.h b/include/net/sock.h index aed436567d70..d6bce19ca261 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -661,6 +661,11 @@ static inline void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_h hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list); } +static inline void __sk_nulls_add_node_tail_rcu(struct sock *sk, struct hlist_nulls_head *list) +{ + hlist_nulls_add_tail_rcu(&sk->sk_nulls_node, list); +} + static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list) { sock_hold(sk); |