Le 25/01/2014 19:36, Steven Rostedt a écrit :
On 3.10.27, loading and then unloading the sit module gives me the
following bug:
[ 35.400878] sit: IPv6 over IPv4 tunneling driver
[ 36.959308] ------------[ cut here ]------------
[ 36.963983] WARNING: at /home/rostedt/work/git/linux-rt.git/lib/list_debug.c:59 __list_del_entry+0xa1/0xd0()
[ 36.973874] list_del corruption. prev->next should be ffff88011656d070, but was ffff880115fe5ea8
[ 36.982684] Modules linked in: sit(-) ip_tunnel tunnel4 bnep lockd bluetooth nf_conntrack_ipv4 ip6t_REJECT nf_defrag_ipv4 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec tpm_infineon snd_hwdep hp_wmi rfkill tpm_tis tpm coretemp snd_seq lpc_ich snd_seq_device snd_pcm sparse_keymap uinput serio_raw pcspkr mfd_core tpm_bios i2c_i801 microcode wmi snd_page_alloc snd_timer snd soundcore i915 e1000e i2c_algo_bit ptp drm_kms_helper crc32c_intel drm pps_core i2c_core video sunrpc
[ 37.034430] CPU: 0 PID: 1071 Comm: rmmod Not tainted 3.10.27-test #143
[ 37.040972] Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
[ 37.049962] ffffffff81a10e78 ffff880115fe5d18 ffffffff8161b3c7 ffff880115fe5d58
[ 37.057439] ffffffff8104b2a0 ffff880115fe5dd8 ffff880115fe5df8 ffff88011656d070
[ 37.064911] 0000000000000080 0000000000000018 ffff880115cb4000 ffff880115fe5db8
[ 37.072405] Call Trace:
[ 37.074869] [<ffffffff8161b3c7>] dump_stack+0x19/0x1b
[ 37.080031] [<ffffffff8104b2a0>] warn_slowpath_common+0x70/0xa0
[ 37.086051] [<ffffffff8104b386>] warn_slowpath_fmt+0x46/0x50
[ 37.091814] [<ffffffff812f56a1>] __list_del_entry+0xa1/0xd0
[ 37.097491] [<ffffffff815168a5>] unregister_netdevice_queue+0x35/0xa0
[ 37.104036] [<ffffffffa038df82>] sit_exit_net+0xc2/0xf0 [sit]
[ 37.109893] [<ffffffff81511278>] ops_exit_list.isra.4+0x38/0x60
[ 37.115917] [<ffffffff815113d0>] unregister_pernet_operations+0x70/0xb0
[ 37.122633] [<ffffffff8151143e>] unregister_pernet_device+0x2e/0x60
[ 37.129005] [<ffffffffa038f86f>] sit_cleanup+0x2d/0x7be [sit]
[ 37.134864] [<ffffffff810b0aee>] SyS_delete_module+0x19e/0x2a0
[ 37.140801] [<ffffffff8162983b>] tracesys+0xdd/0xe2
[ 37.145779] ---[ end trace e45e22e840e55d00 ]---
[ 37.150427] ------------[ cut here ]------------
Investigating differences between 3.10.27 and newer kernels, I found
that the below change is not there. It was part of commit 205983c43700
"sit: allow to use rtnl ops on fb tunnel" which happens to be
backported to 3.10 but in 3.10 backport commit 20300db1bd1b9 this part
of the commit is missing.
Thank you for fixing this. It's the same problem that commit 22c3ec552c29
("ip6tnl: fix use after free of fb_tnl_dev", branch linux-3.10.y).
The upstream commit 205983c43700 ("sit: allow to use rtnl ops on fb tunnel")
(backported into linux-3.10.y) left a bug which was fixed upstream by commit
9434266f2c64 ("sit: fix use after free of fb_tunnel_dev").
The problem is a bit different in linux-3.10.y, because there is no x-netns
support (upstream commit 5e6700b3bf98 ("sit: add support of x-netns")).
When sit.ko is unloaded, FB device is deleted by rtnl_link_unregister()
and then we try to delete it again in sit_exit_net().
When I add this change, the removing of the module no longer gives this
bug.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Acked-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 0491264..02300e8 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1592,7 +1592,6 @@ static void __net_exit sit_exit_net(struct net *net)
rtnl_lock();
sit_destroy_tunnels(sitn, &list);
- unregister_netdevice_queue(sitn->fb_tunnel_dev, &list);
unregister_netdevice_many(&list);
rtnl_unlock();
}
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