From: Herbert Xu <herbert@gondor.apana.org.au>
To: Tejun Heo <tj@kernel.org>
Cc: Cong Wang <cwang@twopensource.com>,
David Miller <davem@davemloft.net>,
Tom Herbert <tom@herbertland.com>,
kafai@fb.com, kernel-team <kernel-team@fb.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jiri Pirko <jiri@resnulli.us>,
Nicolas Dichtel <nicolas.dichtel@6wind.com>,
Thomas Graf <tgraf@suug.ch>, Scott Feldman <sfeldma@gmail.com>
Subject: [PATCH v4] netlink: Fix autobind race condition that leads to zero port ID
Date: Fri, 18 Sep 2015 19:16:50 +0800 [thread overview]
Message-ID: <20150918111650.GA7508@gondor.apana.org.au> (raw)
In-Reply-To: <20150918063609.GA31747@gondor.apana.org.au>
On Fri, Sep 18, 2015 at 02:36:09PM +0800, Herbert Xu wrote:
>
> But yes there are ordering issues here so I've decided to make
> rhashtable use a new field for its hash instead.
>
> Note that I've dropped the acks as this patch is now substantially
> different.
v3 doesn't apply to the current tree anymore so here is a respin
rebased on rc1.
---8<---
The commit c0bb07df7d981e4091432754e30c9c720e2c0c78 ("netlink:
Reset portid after netlink_insert failure") introduced a race
condition where if two threads try to autobind the same socket
one of them may end up with a zero port ID. This led to kernel
deadlocks that were observed by multiple people.
This patch reverts that commit and instead fixes it by introducing
a separte rhash_portid variable so that the real portid is only set
after the socket has been successfully hashed.
Fixes: c0bb07df7d98 ("netlink: Reset portid after netlink_insert failure")
Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 7f86d3b..303efb7 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1015,7 +1015,7 @@ static inline int netlink_compare(struct rhashtable_compare_arg *arg,
const struct netlink_compare_arg *x = arg->key;
const struct netlink_sock *nlk = ptr;
- return nlk->portid != x->portid ||
+ return nlk->rhash_portid != x->portid ||
!net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
}
@@ -1041,7 +1041,7 @@ static int __netlink_insert(struct netlink_table *table, struct sock *sk)
{
struct netlink_compare_arg arg;
- netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
+ netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->rhash_portid);
return rhashtable_lookup_insert_key(&table->hash, &arg,
&nlk_sk(sk)->node,
netlink_rhashtable_params);
@@ -1103,7 +1103,7 @@ static int netlink_insert(struct sock *sk, u32 portid)
unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX))
goto err;
- nlk_sk(sk)->portid = portid;
+ nlk_sk(sk)->rhash_portid = portid;
sock_hold(sk);
err = __netlink_insert(table, sk);
@@ -1115,10 +1115,12 @@ static int netlink_insert(struct sock *sk, u32 portid)
err = -EOVERFLOW;
if (err == -EEXIST)
err = -EADDRINUSE;
- nlk_sk(sk)->portid = 0;
sock_put(sk);
+ goto err;
}
+ nlk_sk(sk)->portid = portid;
+
err:
release_sock(sk);
return err;
@@ -3255,7 +3257,7 @@ static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
const struct netlink_sock *nlk = data;
struct netlink_compare_arg arg;
- netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
+ netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->rhash_portid);
return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
}
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index 8900840..c96dfa3 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -25,6 +25,7 @@ struct netlink_ring {
struct netlink_sock {
/* struct sock has to be the first member of netlink_sock */
struct sock sk;
+ u32 rhash_portid;
u32 portid;
u32 dst_portid;
u32 dst_group;
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2015-09-18 11:17 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-17 2:29 Possible netlink autobind regression Tejun Heo
2015-09-17 3:08 ` Herbert Xu
2015-09-17 3:41 ` Herbert Xu
2015-09-17 5:02 ` Cong Wang
2015-09-17 5:15 ` Herbert Xu
2015-09-17 11:25 ` Thomas Graf
2015-09-17 11:30 ` Tejun Heo
2015-09-18 6:36 ` [PATCH v3] netlink: Fix autobind race condition that leads to zero port ID Herbert Xu
2015-09-18 11:16 ` Herbert Xu [this message]
2015-09-21 5:55 ` [PATCH v4] " David Miller
2015-09-21 6:06 ` Herbert Xu
2015-09-21 6:11 ` David Miller
2015-09-21 13:34 ` netlink: Replace rhash_portid with bound Herbert Xu
2015-09-21 18:20 ` Tejun Heo
2015-09-22 3:38 ` [PATCH v2] " Herbert Xu
2015-09-22 16:10 ` Tejun Heo
2015-09-22 18:42 ` Linus Torvalds
2015-09-22 18:53 ` Tejun Heo
2015-09-22 19:28 ` Linus Torvalds
2015-09-22 19:50 ` Tejun Heo
2015-09-22 20:03 ` Linus Torvalds
2015-09-22 20:36 ` Bjørn Mork
2015-09-22 21:04 ` Linus Torvalds
2015-09-23 6:13 ` Herbert Xu
2015-09-23 15:54 ` Tejun Heo
2015-09-24 2:30 ` Herbert Xu
2015-09-24 2:46 ` Tejun Heo
2015-09-24 2:54 ` Herbert Xu
2015-09-24 3:06 ` Tejun Heo
2015-09-24 3:21 ` Herbert Xu
2015-09-24 3:29 ` Tejun Heo
2015-09-24 3:31 ` Herbert Xu
2015-09-24 3:41 ` Tejun Heo
2015-09-24 3:42 ` Herbert Xu
2015-09-24 3:43 ` Tejun Heo
2015-09-24 3:44 ` Herbert Xu
2015-09-24 19:11 ` David Miller
2015-09-24 20:05 ` Tejun Heo
2015-09-25 1:43 ` netlink: Add barrier to netlink_connect for theoretical case Herbert Xu
2015-09-25 3:24 ` Linus Torvalds
2015-09-25 3:39 ` Herbert Xu
2015-09-25 15:09 ` Tejun Heo
2015-09-25 15:01 ` Tejun Heo
2015-09-26 13:16 ` netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu
2015-09-26 18:09 ` Tejun Heo
2015-09-26 19:41 ` Herbert Xu
2015-09-26 19:45 ` Tejun Heo
2015-09-26 19:49 ` Herbert Xu
2015-09-26 19:52 ` Tejun Heo
2015-09-26 19:55 ` Herbert Xu
2015-09-26 20:05 ` Tejun Heo
2015-09-26 20:10 ` Herbert Xu
2015-09-26 20:17 ` Tejun Heo
2015-09-21 20:52 ` [PATCH] netlink: Replace rhash_portid with load_acquire protected boolean Tejun Heo
2015-09-18 13:37 ` [PATCH v3] netlink: Fix autobind race condition that leads to zero port ID Tejun Heo
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