Patch "net: openvswitch: fix race on port output" has been added to the 6.2-stable tree

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This is a note to let you know that I've just added the patch titled

    net: openvswitch: fix race on port output

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-openvswitch-fix-race-on-port-output.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 35ac58d3b597c4049ced08d787fc16a88ddfe6ef
Author: Felix Huettner <felix.huettner@mail.schwarz>
Date:   Wed Apr 5 07:53:41 2023 +0000

    net: openvswitch: fix race on port output
    
    [ Upstream commit 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 ]
    
    assume the following setup on a single machine:
    1. An openvswitch instance with one bridge and default flows
    2. two network namespaces "server" and "client"
    3. two ovs interfaces "server" and "client" on the bridge
    4. for each ovs interface a veth pair with a matching name and 32 rx and
       tx queues
    5. move the ends of the veth pairs to the respective network namespaces
    6. assign ip addresses to each of the veth ends in the namespaces (needs
       to be the same subnet)
    7. start some http server on the server network namespace
    8. test if a client in the client namespace can reach the http server
    
    when following the actions below the host has a chance of getting a cpu
    stuck in a infinite loop:
    1. send a large amount of parallel requests to the http server (around
       3000 curls should work)
    2. in parallel delete the network namespace (do not delete interfaces or
       stop the server, just kill the namespace)
    
    there is a low chance that this will cause the below kernel cpu stuck
    message. If this does not happen just retry.
    Below there is also the output of bpftrace for the functions mentioned
    in the output.
    
    The series of events happening here is:
    1. the network namespace is deleted calling
       `unregister_netdevice_many_notify` somewhere in the process
    2. this sets first `NETREG_UNREGISTERING` on both ends of the veth and
       then runs `synchronize_net`
    3. it then calls `call_netdevice_notifiers` with `NETDEV_UNREGISTER`
    4. this is then handled by `dp_device_event` which calls
       `ovs_netdev_detach_dev` (if a vport is found, which is the case for
       the veth interface attached to ovs)
    5. this removes the rx_handlers of the device but does not prevent
       packages to be sent to the device
    6. `dp_device_event` then queues the vport deletion to work in
       background as a ovs_lock is needed that we do not hold in the
       unregistration path
    7. `unregister_netdevice_many_notify` continues to call
       `netdev_unregister_kobject` which sets `real_num_tx_queues` to 0
    8. port deletion continues (but details are not relevant for this issue)
    9. at some future point the background task deletes the vport
    
    If after 7. but before 9. a packet is send to the ovs vport (which is
    not deleted at this point in time) which forwards it to the
    `dev_queue_xmit` flow even though the device is unregistering.
    In `skb_tx_hash` (which is called in the `dev_queue_xmit`) path there is
    a while loop (if the packet has a rx_queue recorded) that is infinite if
    `dev->real_num_tx_queues` is zero.
    
    To prevent this from happening we update `do_output` to handle devices
    without carrier the same as if the device is not found (which would
    be the code path after 9. is done).
    
    Additionally we now produce a warning in `skb_tx_hash` if we will hit
    the infinite loop.
    
    bpftrace (first word is function name):
    
    __dev_queue_xmit server: real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
    netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 1, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 1
    dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 2, reg_state: 1
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 6, reg_state: 2
    ovs_netdev_detach_dev server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, reg_state: 2
    netdev_rx_handler_unregister server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    netdev_rx_handler_unregister ret server: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024, reg_state: 2
    dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 27, reg_state: 2
    dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 22, reg_state: 2
    dp_device_event server: real_num_tx_queues: 1 cpu 9, pid: 21024, tid: 21024, event 18, reg_state: 2
    netdev_unregister_kobject: real_num_tx_queues: 1, cpu: 9, pid: 21024, tid: 21024
    synchronize_rcu_expedited: cpu 9, pid: 21024, tid: 21024
    ovs_vport_send server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
    __dev_queue_xmit server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
    netdev_core_pick_tx server: addr: 0xffff9f0a46d4a000 real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024, skb_addr: 0xffff9edb6f207000, reg_state: 2
    broken device server: real_num_tx_queues: 0, cpu: 2, pid: 28024, tid: 28024
    ovs_dp_detach_port server: real_num_tx_queues: 0 cpu 9, pid: 9124, tid: 9124, reg_state: 2
    synchronize_rcu_expedited: cpu 9, pid: 33604, tid: 33604
    
    stuck message:
    
    watchdog: BUG: soft lockup - CPU#5 stuck for 26s! [curl:1929279]
    Modules linked in: veth pktgen bridge stp llc ip_set_hash_net nft_counter xt_set nft_compat nf_tables ip_set_hash_ip ip_set nfnetlink_cttimeout nfnetlink openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 tls binfmt_misc nls_iso8859_1 input_leds joydev serio_raw dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua sch_fq_codel drm efi_pstore virtio_rng ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel virtio_net ahci net_failover crypto_simd cryptd psmouse libahci virtio_blk failover
    CPU: 5 PID: 1929279 Comm: curl Not tainted 5.15.0-67-generic #74-Ubuntu
    Hardware name: OpenStack Foundation OpenStack Nova, BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
    RIP: 0010:netdev_pick_tx+0xf1/0x320
    Code: 00 00 8d 48 ff 0f b7 c1 66 39 ca 0f 86 e9 01 00 00 45 0f b7 ff 41 39 c7 0f 87 5b 01 00 00 44 29 f8 41 39 c7 0f 87 4f 01 00 00 <eb> f2 0f 1f 44 00 00 49 8b 94 24 28 04 00 00 48 85 d2 0f 84 53 01
    RSP: 0018:ffffb78b40298820 EFLAGS: 00000246
    RAX: 0000000000000000 RBX: ffff9c8773adc2e0 RCX: 000000000000083f
    RDX: 0000000000000000 RSI: ffff9c8773adc2e0 RDI: ffff9c870a25e000
    RBP: ffffb78b40298858 R08: 0000000000000001 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: ffff9c870a25e000
    R13: ffff9c870a25e000 R14: ffff9c87fe043480 R15: 0000000000000000
    FS:  00007f7b80008f00(0000) GS:ffff9c8e5f740000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007f7b80f6a0b0 CR3: 0000000329d66000 CR4: 0000000000350ee0
    Call Trace:
     <IRQ>
     netdev_core_pick_tx+0xa4/0xb0
     __dev_queue_xmit+0xf8/0x510
     ? __bpf_prog_exit+0x1e/0x30
     dev_queue_xmit+0x10/0x20
     ovs_vport_send+0xad/0x170 [openvswitch]
     do_output+0x59/0x180 [openvswitch]
     do_execute_actions+0xa80/0xaa0 [openvswitch]
     ? kfree+0x1/0x250
     ? kfree+0x1/0x250
     ? kprobe_perf_func+0x4f/0x2b0
     ? flow_lookup.constprop.0+0x5c/0x110 [openvswitch]
     ovs_execute_actions+0x4c/0x120 [openvswitch]
     ovs_dp_process_packet+0xa1/0x200 [openvswitch]
     ? ovs_ct_update_key.isra.0+0xa8/0x120 [openvswitch]
     ? ovs_ct_fill_key+0x1d/0x30 [openvswitch]
     ? ovs_flow_key_extract+0x2db/0x350 [openvswitch]
     ovs_vport_receive+0x77/0xd0 [openvswitch]
     ? __htab_map_lookup_elem+0x4e/0x60
     ? bpf_prog_680e8aff8547aec1_kfree+0x3b/0x714
     ? trace_call_bpf+0xc8/0x150
     ? kfree+0x1/0x250
     ? kfree+0x1/0x250
     ? kprobe_perf_func+0x4f/0x2b0
     ? kprobe_perf_func+0x4f/0x2b0
     ? __mod_memcg_lruvec_state+0x63/0xe0
     netdev_port_receive+0xc4/0x180 [openvswitch]
     ? netdev_port_receive+0x180/0x180 [openvswitch]
     netdev_frame_hook+0x1f/0x40 [openvswitch]
     __netif_receive_skb_core.constprop.0+0x23d/0xf00
     __netif_receive_skb_one_core+0x3f/0xa0
     __netif_receive_skb+0x15/0x60
     process_backlog+0x9e/0x170
     __napi_poll+0x33/0x180
     net_rx_action+0x126/0x280
     ? ttwu_do_activate+0x72/0xf0
     __do_softirq+0xd9/0x2e7
     ? rcu_report_exp_cpu_mult+0x1b0/0x1b0
     do_softirq+0x7d/0xb0
     </IRQ>
     <TASK>
     __local_bh_enable_ip+0x54/0x60
     ip_finish_output2+0x191/0x460
     __ip_finish_output+0xb7/0x180
     ip_finish_output+0x2e/0xc0
     ip_output+0x78/0x100
     ? __ip_finish_output+0x180/0x180
     ip_local_out+0x5e/0x70
     __ip_queue_xmit+0x184/0x440
     ? tcp_syn_options+0x1f9/0x300
     ip_queue_xmit+0x15/0x20
     __tcp_transmit_skb+0x910/0x9c0
     ? __mod_memcg_state+0x44/0xa0
     tcp_connect+0x437/0x4e0
     ? ktime_get_with_offset+0x60/0xf0
     tcp_v4_connect+0x436/0x530
     __inet_stream_connect+0xd4/0x3a0
     ? kprobe_perf_func+0x4f/0x2b0
     ? aa_sk_perm+0x43/0x1c0
     inet_stream_connect+0x3b/0x60
     __sys_connect_file+0x63/0x70
     __sys_connect+0xa6/0xd0
     ? setfl+0x108/0x170
     ? do_fcntl+0xe8/0x5a0
     __x64_sys_connect+0x18/0x20
     do_syscall_64+0x5c/0xc0
     ? __x64_sys_fcntl+0xa9/0xd0
     ? exit_to_user_mode_prepare+0x37/0xb0
     ? syscall_exit_to_user_mode+0x27/0x50
     ? do_syscall_64+0x69/0xc0
     ? __sys_setsockopt+0xea/0x1e0
     ? exit_to_user_mode_prepare+0x37/0xb0
     ? syscall_exit_to_user_mode+0x27/0x50
     ? __x64_sys_setsockopt+0x1f/0x30
     ? do_syscall_64+0x69/0xc0
     ? irqentry_exit+0x1d/0x30
     ? exc_page_fault+0x89/0x170
     entry_SYSCALL_64_after_hwframe+0x61/0xcb
    RIP: 0033:0x7f7b8101c6a7
    Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 18 89 54 24 0c 48 89 34 24 89
    RSP: 002b:00007ffffd6b2198 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
    RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7b8101c6a7
    RDX: 0000000000000010 RSI: 00007ffffd6b2360 RDI: 0000000000000005
    RBP: 0000561f1370d560 R08: 00002795ad21d1ac R09: 0030312e302e302e
    R10: 00007ffffd73f080 R11: 0000000000000246 R12: 0000561f1370c410
    R13: 0000000000000000 R14: 0000000000000005 R15: 0000000000000000
     </TASK>
    
    Fixes: 7f8a436eaa2c ("openvswitch: Add conntrack action")
    Co-developed-by: Luca Czesla <luca.czesla@mail.schwarz>
    Signed-off-by: Luca Czesla <luca.czesla@mail.schwarz>
    Signed-off-by: Felix Huettner <felix.huettner@mail.schwarz>
    Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/ZC0pBXBAgh7c76CA@kernel-bug-kernel-bug
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/core/dev.c b/net/core/dev.c
index fce980d531bdc..127815273ce3c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3196,6 +3196,7 @@ static u16 skb_tx_hash(const struct net_device *dev,
 	}
 
 	if (skb_rx_queue_recorded(skb)) {
+		DEBUG_NET_WARN_ON_ONCE(qcount == 0);
 		hash = skb_get_rx_queue(skb);
 		if (hash >= qoffset)
 			hash -= qoffset;
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index ca3ebfdb30231..a8cf9a88758ef 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -913,7 +913,7 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
 {
 	struct vport *vport = ovs_vport_rcu(dp, out_port);
 
-	if (likely(vport)) {
+	if (likely(vport && netif_carrier_ok(vport->dev))) {
 		u16 mru = OVS_CB(skb)->mru;
 		u32 cutlen = OVS_CB(skb)->cutlen;
 



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