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Message-ID: <FD16AC44-E1DA-4E6A-AE3E-905D55AB1A7D@redhat.com>
Date: Mon, 05 Jun 2023 14:54:35 +0200
From: Eelco Chaudron <echaudro@...hat.com>
To: Simon Horman <simon.horman@...igine.com>
Cc: netdev@...r.kernel.org, dev@...nvswitch.org, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, davem@...emloft.net
Subject: Re: [ovs-dev] [PATCH net] net: openvswitch: fix upcall counter access
before allocation
On 5 Jun 2023, at 14:41, Simon Horman wrote:
> On Mon, Jun 05, 2023 at 10:59:50AM +0200, Eelco Chaudron wrote:
>> Currently, the per cpu upcall counters are allocated after the vport is
>> created and inserted into the system. This could lead to the datapath
>> accessing the counters before they are allocated resulting in a kernel
>> Oops.
>>
>> Here is an example:
>>
>> PID: 59693 TASK: ffff0005f4f51500 CPU: 0 COMMAND: "ovs-vswitchd"
>> #0 [ffff80000a39b5b0] __switch_to at ffffb70f0629f2f4
>> #1 [ffff80000a39b5d0] __schedule at ffffb70f0629f5cc
>> #2 [ffff80000a39b650] preempt_schedule_common at ffffb70f0629fa60
>> #3 [ffff80000a39b670] dynamic_might_resched at ffffb70f0629fb58
>> #4 [ffff80000a39b680] mutex_lock_killable at ffffb70f062a1388
>> #5 [ffff80000a39b6a0] pcpu_alloc at ffffb70f0594460c
>> #6 [ffff80000a39b750] __alloc_percpu_gfp at ffffb70f05944e68
>> #7 [ffff80000a39b760] ovs_vport_cmd_new at ffffb70ee6961b90 [openvswitch]
>> ...
>>
>> PID: 58682 TASK: ffff0005b2f0bf00 CPU: 0 COMMAND: "kworker/0:3"
>> #0 [ffff80000a5d2f40] machine_kexec at ffffb70f056a0758
>> #1 [ffff80000a5d2f70] __crash_kexec at ffffb70f057e2994
>> #2 [ffff80000a5d3100] crash_kexec at ffffb70f057e2ad8
>> #3 [ffff80000a5d3120] die at ffffb70f0628234c
>> #4 [ffff80000a5d31e0] die_kernel_fault at ffffb70f062828a8
>> #5 [ffff80000a5d3210] __do_kernel_fault at ffffb70f056a31f4
>> #6 [ffff80000a5d3240] do_bad_area at ffffb70f056a32a4
>> #7 [ffff80000a5d3260] do_translation_fault at ffffb70f062a9710
>> #8 [ffff80000a5d3270] do_mem_abort at ffffb70f056a2f74
>> #9 [ffff80000a5d32a0] el1_abort at ffffb70f06297dac
>> #10 [ffff80000a5d32d0] el1h_64_sync_handler at ffffb70f06299b24
>> #11 [ffff80000a5d3410] el1h_64_sync at ffffb70f056812dc
>> #12 [ffff80000a5d3430] ovs_dp_upcall at ffffb70ee6963c84 [openvswitch]
>> #13 [ffff80000a5d3470] ovs_dp_process_packet at ffffb70ee6963fdc [openvswitch]
>> #14 [ffff80000a5d34f0] ovs_vport_receive at ffffb70ee6972c78 [openvswitch]
>> #15 [ffff80000a5d36f0] netdev_port_receive at ffffb70ee6973948 [openvswitch]
>> #16 [ffff80000a5d3720] netdev_frame_hook at ffffb70ee6973a28 [openvswitch]
>> #17 [ffff80000a5d3730] __netif_receive_skb_core.constprop.0 at ffffb70f06079f90
>>
>> We moved the per cpu upcall counter allocation to the existing vport
>> alloc and free functions to solve this.
>>
>> Fixes: 95637d91fefd ("net: openvswitch: release vport resources on failure")
>> Fixes: 1933ea365aa7 ("net: openvswitch: Add support to count upcall packets")
>> Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
>> ---
>> net/openvswitch/datapath.c | 19 -------------------
>> net/openvswitch/vport.c | 8 ++++++++
>> 2 files changed, 8 insertions(+), 19 deletions(-)
>>
>> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
>> index fcee6012293b..58f530f60172 100644
>> --- a/net/openvswitch/datapath.c
>> +++ b/net/openvswitch/datapath.c
>> @@ -236,9 +236,6 @@ void ovs_dp_detach_port(struct vport *p)
>> /* First drop references to device. */
>> hlist_del_rcu(&p->dp_hash_node);
>>
>> - /* Free percpu memory */
>> - free_percpu(p->upcall_stats);
>> -
>> /* Then destroy it. */
>> ovs_vport_del(p);
>> }
>> @@ -1858,12 +1855,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>> goto err_destroy_portids;
>> }
>>
>> - vport->upcall_stats = netdev_alloc_pcpu_stats(struct vport_upcall_stats_percpu);
>> - if (!vport->upcall_stats) {
>> - err = -ENOMEM;
>> - goto err_destroy_vport;
>> - }
>> -
>> err = ovs_dp_cmd_fill_info(dp, reply, info->snd_portid,
>> info->snd_seq, 0, OVS_DP_CMD_NEW);
>> BUG_ON(err < 0);
>> @@ -1876,8 +1867,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>> ovs_notify(&dp_datapath_genl_family, reply, info);
>> return 0;
>>
>> -err_destroy_vport:
>> - ovs_dp_detach_port(vport);
>> err_destroy_portids:
>> kfree(rcu_dereference_raw(dp->upcall_portids));
>> err_unlock_and_destroy_meters:
>> @@ -2322,12 +2311,6 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
>> goto exit_unlock_free;
>> }
>>
>> - vport->upcall_stats = netdev_alloc_pcpu_stats(struct vport_upcall_stats_percpu);
>> - if (!vport->upcall_stats) {
>> - err = -ENOMEM;
>> - goto exit_unlock_free_vport;
>> - }
>> -
>> err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
>> info->snd_portid, info->snd_seq, 0,
>> OVS_VPORT_CMD_NEW, GFP_KERNEL);
>> @@ -2345,8 +2328,6 @@ static int ovs_vport_cmd_new(struct sk_buff *skb, struct genl_info *info)
>> ovs_notify(&dp_vport_genl_family, reply, info);
>> return 0;
>>
>> -exit_unlock_free_vport:
>> - ovs_dp_detach_port(vport);
>> exit_unlock_free:
>> ovs_unlock();
>> kfree_skb(reply);
>> diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
>> index 7e0f5c45b512..e91ae5dd7d22 100644
>> --- a/net/openvswitch/vport.c
>> +++ b/net/openvswitch/vport.c
>
> Hi Eelco,
>
> could we move to a more idiomatic implementation
> of the error path in ovs_vport_alloc() ?
>
> I know it's not strictly related to this change, but OTOH, it is.
Thanks Simon for the review…
I decided to stick to fixing the issue, not trying to do cleanup stuff while at it :) But if there are no further comments by tomorrow, I can send a v2 including this change.
>
>> @@ -135,12 +135,19 @@ struct vport *ovs_vport_alloc(int priv_size, const struct vport_ops *ops,
>> if (!vport)
>> return ERR_PTR(-ENOMEM);
>>
>> + vport->upcall_stats = netdev_alloc_pcpu_stats(struct vport_upcall_stats_percpu);
>> + if (!vport->upcall_stats) {
> err = -ENOMEM;
> goto err_kfree_vport;
>
>> + kfree(vport);
>> + return ERR_PTR(-ENOMEM);
>> + }
>> +
>> vport->dp = parms->dp;
>> vport->port_no = parms->port_no;
>> vport->ops = ops;
>> INIT_HLIST_NODE(&vport->dp_hash_node);
>>
>> if (ovs_vport_set_upcall_portids(vport, parms->upcall_portids)) {
> err = -EINVAL;
> goto err_free_percpu;
>
>> + free_percpu(vport->upcall_stats);
>> kfree(vport);
>> return ERR_PTR(-EINVAL);
>> }
>
> ...
> return vport;
>
> err_kfree_vport:
> kfree(vport);
> err_free_percpu:
> free_percpu(vport->upcall_stats);
> return(ERR_PTR(err));
>
>
>> @@ -165,6 +172,7 @@ void ovs_vport_free(struct vport *vport)
>> * it is safe to use raw dereference.
>> */
>> kfree(rcu_dereference_raw(vport->upcall_portids));
>> + free_percpu(vport->upcall_stats);
>> kfree(vport);
>> }
>> EXPORT_SYMBOL_GPL(ovs_vport_free);
>>
>> _______________________________________________
>> dev mailing list
>> dev@...nvswitch.org
>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>
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