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Message-ID: <ZH3X/lLNwfAIZfdq@corigine.com>
Date: Mon, 5 Jun 2023 14:41:34 +0200
From: Simon Horman <simon.horman@...igine.com>
To: Eelco Chaudron <echaudro@...hat.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 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.
> @@ -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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