From: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
To: Guillaume Nault <gnault@redhat.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL] in vrf "bind - ns-B IPv6 LLA" test
Date: Tue, 6 Jun 2023 16:28:02 +0200 [thread overview]
Message-ID: <12c34bed-0885-3bb3-257f-3b2438ba206f@alu.unizg.hr> (raw)
In-Reply-To: <ZH8+jLjottBw2zuD@debian>
On 6/6/23 16:11, Guillaume Nault wrote:
> On Tue, Jun 06, 2023 at 03:57:35PM +0200, Mirsad Todorovac wrote:
>> diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
>> index c4835dbdfcff..c1d81c49b775 100644
>> --- a/net/ipv6/ping.c
>> +++ b/net/ipv6/ping.c
>> @@ -73,6 +73,10 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> struct rt6_info *rt;
>> struct pingfakehdr pfh;
>> struct ipcm6_cookie ipc6;
>> + struct net *net = sock_net(sk);
>> + struct net_device *dev = NULL;
>> + struct net_device *mdev = NULL;
>> + struct net_device *bdev = NULL;
>>
>> err = ping_common_sendmsg(AF_INET6, msg, len, &user_icmph,
>> sizeof(user_icmph));
>> @@ -111,10 +115,26 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> else if (!oif)
>> oif = np->ucast_oif;
>>
>> + if (oif) {
>> + rcu_read_lock();
>> + dev = dev_get_by_index_rcu(net, oif);
>> + rcu_read_unlock();
>
> You can't assume '*dev' is still valid after rcu_read_unlock() unless
> you hold a reference on it.
>
>> + rtnl_lock();
>> + mdev = netdev_master_upper_dev_get(dev);
>> + rtnl_unlock();
>
> Because of that, 'dev' might have already disappeared at the time
> netdev_master_upper_dev_get() is called. So it may dereference an
> invalid pointer here.
Good point, thanks. I didn't expect those to change.
This can be fixed, provided that RCU and RTNL locks can be nested:
rcu_read_lock();
if (oif) {
dev = dev_get_by_index_rcu(net, oif);
rtnl_lock();
mdev = netdev_master_upper_dev_get(dev);
rtnl_unlock();
}
if (sk->sk_bound_dev_if) {
bdev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
}
addr_type = ipv6_addr_type(daddr);
if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
(addr_type & IPV6_ADDR_MAPPED) ||
(oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if &&
!(mdev && sk->sk_bound_dev_if && bdev && mdev == bdev))) {
rcu_read_unlock();
return -EINVAL;
}
rcu_read_unlock();
But again this is still probably not race-free (bdev might also disappear before
the mdev == bdev test), even if it passed fcnal-test.sh, there is much duplication
of code, so your one-line solution is obviously by far better. :-)
Much obliged.
Best regards,
Mirsad
>> + }
>> +
>> + if (sk->sk_bound_dev_if) {
>> + rcu_read_lock();
>> + bdev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
>> + rcu_read_unlock();
>> + }
>> +
>> addr_type = ipv6_addr_type(daddr);
>> if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
>> (addr_type & IPV6_ADDR_MAPPED) ||
>> - (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if))
>> + (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if &&
>> + !(mdev && sk->sk_bound_dev_if && bdev && mdev == bdev)))
>> return -EINVAL;
>>
>> ipcm6_init_sk(&ipc6, np);
>>
>> However, this works by the test (888 passed) but your two liner is obviously
>> better :-)
>
> :)
--
Mirsad Goran Todorovac
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
next prev parent reply other threads:[~2023-06-06 14:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-24 12:17 POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL] in vrf "bind - ns-B IPv6 LLA" test Mirsad Todorovac
2023-05-31 18:11 ` Guillaume Nault
2023-06-02 12:35 ` Mirsad Goran Todorovac
2023-06-06 6:24 ` Mirsad Goran Todorovac
2023-06-06 13:46 ` Guillaume Nault
2023-06-06 13:57 ` Mirsad Todorovac
2023-06-06 14:11 ` Guillaume Nault
2023-06-06 14:28 ` Mirsad Todorovac [this message]
2023-06-06 18:50 ` Guillaume Nault
2023-06-06 19:17 ` Mirsad Goran Todorovac
2023-06-06 19:27 ` Guillaume Nault
2023-06-06 18:07 ` POSSIBLE BUG: selftests/net/fcnal-test.sh: [FAIL][FIX TESTED] " Mirsad Goran Todorovac
2023-06-06 18:57 ` Guillaume Nault
2023-06-06 22:04 ` Mirsad Goran Todorovac
2023-06-07 16:51 ` Guillaume Nault
2023-06-08 5:37 ` Mirsad Goran Todorovac
2023-06-09 16:13 ` Guillaume Nault
2023-06-10 18:04 ` Mirsad Goran Todorovac
2023-06-14 8:47 ` Guillaume Nault
2023-06-15 20:10 ` Mirsad Goran Todorovac
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