<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/net/core/dev.c, branch v5.4.113</title>
<subtitle>Linux Kernel
</subtitle>
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<updated>2021-03-30T12:35:29Z</updated>
<entry>
<title>can: dev: Move device back to init netns on owning netns delete</title>
<updated>2021-03-30T12:35:29Z</updated>
<author>
<name>Martin Willi</name>
<email>martin@strongswan.org</email>
</author>
<published>2021-03-02T12:24:23Z</published>
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<id>urn:sha1:f866d1fa48e40af651d9c78b7f3c5a9a6ccf1815</id>
<content type='text'>
commit 3a5ca857079ea022e0b1b17fc154f7ad7dbc150f upstream.

When a non-initial netns is destroyed, the usual policy is to delete
all virtual network interfaces contained, but move physical interfaces
back to the initial netns. This keeps the physical interface visible
on the system.

CAN devices are somewhat special, as they define rtnl_link_ops even
if they are physical devices. If a CAN interface is moved into a
non-initial netns, destroying that netns lets the interface vanish
instead of moving it back to the initial netns. default_device_exit()
skips CAN interfaces due to having rtnl_link_ops set. Reproducer:

  ip netns add foo
  ip link set can0 netns foo
  ip netns delete foo

WARNING: CPU: 1 PID: 84 at net/core/dev.c:11030 ops_exit_list+0x38/0x60
CPU: 1 PID: 84 Comm: kworker/u4:2 Not tainted 5.10.19 #1
Workqueue: netns cleanup_net
[&lt;c010e700&gt;] (unwind_backtrace) from [&lt;c010a1d8&gt;] (show_stack+0x10/0x14)
[&lt;c010a1d8&gt;] (show_stack) from [&lt;c086dc10&gt;] (dump_stack+0x94/0xa8)
[&lt;c086dc10&gt;] (dump_stack) from [&lt;c086b938&gt;] (__warn+0xb8/0x114)
[&lt;c086b938&gt;] (__warn) from [&lt;c086ba10&gt;] (warn_slowpath_fmt+0x7c/0xac)
[&lt;c086ba10&gt;] (warn_slowpath_fmt) from [&lt;c0629f20&gt;] (ops_exit_list+0x38/0x60)
[&lt;c0629f20&gt;] (ops_exit_list) from [&lt;c062a5c4&gt;] (cleanup_net+0x230/0x380)
[&lt;c062a5c4&gt;] (cleanup_net) from [&lt;c0142c20&gt;] (process_one_work+0x1d8/0x438)
[&lt;c0142c20&gt;] (process_one_work) from [&lt;c0142ee4&gt;] (worker_thread+0x64/0x5a8)
[&lt;c0142ee4&gt;] (worker_thread) from [&lt;c0148a98&gt;] (kthread+0x148/0x14c)
[&lt;c0148a98&gt;] (kthread) from [&lt;c0100148&gt;] (ret_from_fork+0x14/0x2c)

To properly restore physical CAN devices to the initial netns on owning
netns exit, introduce a flag on rtnl_link_ops that can be set by drivers.
For CAN devices setting this flag, default_device_exit() considers them
non-virtual, applying the usual namespace move.

The issue was introduced in the commit mentioned below, as at that time
CAN devices did not have a dellink() operation.

Fixes: e008b5fc8dc7 ("net: Simplfy default_device_exit and improve batching.")
Link: https://lore.kernel.org/r/20210302122423.872326-1-martin@strongswan.org
Signed-off-by: Martin Willi &lt;martin@strongswan.org&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: fix dev_ifsioc_locked() race condition</title>
<updated>2021-03-07T11:20:43Z</updated>
<author>
<name>Cong Wang</name>
<email>cong.wang@bytedance.com</email>
</author>
<published>2021-02-11T19:34:10Z</published>
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<id>urn:sha1:176188cff67ec1aa55103647b61d02315cc38e98</id>
<content type='text'>
commit 3b23a32a63219f51a5298bc55a65ecee866e79d0 upstream.

dev_ifsioc_locked() is called with only RCU read lock, so when
there is a parallel writer changing the mac address, it could
get a partially updated mac address, as shown below:

Thread 1			Thread 2
// eth_commit_mac_addr_change()
memcpy(dev-&gt;dev_addr, addr-&gt;sa_data, ETH_ALEN);
				// dev_ifsioc_locked()
				memcpy(ifr-&gt;ifr_hwaddr.sa_data,
					dev-&gt;dev_addr,...);

Close this race condition by guarding them with a RW semaphore,
like netdev_get_name(). We can not use seqlock here as it does not
allow blocking. The writers already take RTNL anyway, so this does
not affect the slow path. To avoid bothering existing
dev_set_mac_address() callers in drivers, introduce a new wrapper
just for user-facing callers on ioctl and rtnetlink paths.

Note, bonding also changes slave mac addresses but that requires
a separate patch due to the complexity of bonding code.

Fixes: 3710becf8a58 ("net: RCU locking for simple ioctl()")
Reported-by: "Gong, Sishuai" &lt;sishuai@purdue.edu&gt;
Cc: Eric Dumazet &lt;eric.dumazet@gmail.com&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Cong Wang &lt;cong.wang@bytedance.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: gro: do not keep too many GRO packets in napi-&gt;rx_list</title>
<updated>2021-02-17T09:35:19Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-02-04T21:31:46Z</published>
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<id>urn:sha1:2085d886630a5efab216e677d03b51916cd77ff1</id>
<content type='text'>
commit 8dc1c444df193701910f5e80b5d4caaf705a8fb0 upstream.

Commit c80794323e82 ("net: Fix packet reordering caused by GRO and
listified RX cooperation") had the unfortunate effect of adding
latencies in common workloads.

Before the patch, GRO packets were immediately passed to
upper stacks.

After the patch, we can accumulate quite a lot of GRO
packets (depdending on NAPI budget).

My fix is counting in napi-&gt;rx_count number of segments
instead of number of logical packets.

Fixes: c80794323e82 ("net: Fix packet reordering caused by GRO and listified RX cooperation")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Bisected-by: John Sperbeck &lt;jsperbeck@google.com&gt;
Tested-by: Jian Yang &lt;jianyang@google.com&gt;
Cc: Maxim Mikityanskiy &lt;maximmi@mellanox.com&gt;
Reviewed-by: Saeed Mahameed &lt;saeedm@nvidia.com&gt;
Reviewed-by: Edward Cree &lt;ecree.xilinx@gmail.com&gt;
Reviewed-by: Alexander Lobakin &lt;alobakin@pm.me&gt;
Link: https://lore.kernel.org/r/20210204213146.4192368-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: Disable NETIF_F_HW_TLS_RX when RXCSUM is disabled</title>
<updated>2021-01-27T10:47:54Z</updated>
<author>
<name>Tariq Toukan</name>
<email>tariqt@nvidia.com</email>
</author>
<published>2021-01-17T15:15:38Z</published>
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<id>urn:sha1:ff64094dc71823938acb595cab27a4b07d6a6cd1</id>
<content type='text'>
commit a3eb4e9d4c9218476d05c52dfd2be3d6fdce6b91 upstream.

With NETIF_F_HW_TLS_RX packets are decrypted in HW. This cannot be
logically done when RXCSUM offload is off.

Fixes: 14136564c8ee ("net: Add TLS RX offload feature")
Signed-off-by: Tariq Toukan &lt;tariqt@nvidia.com&gt;
Reviewed-by: Boris Pismenny &lt;borisp@nvidia.com&gt;
Link: https://lore.kernel.org/r/20210117151538.9411-1-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>net: Fix bridge enslavement failure</title>
<updated>2020-09-26T16:03:13Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2020-09-10T11:01:26Z</published>
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<id>urn:sha1:d3c2188ee6e644c5159422cbdc892a21653ad38d</id>
<content type='text'>
[ Upstream commit e1b9efe6baebe79019a2183176686a0e709388ae ]

When a netdev is enslaved to a bridge, its parent identifier is queried.
This is done so that packets that were already forwarded in hardware
will not be forwarded again by the bridge device between netdevs
belonging to the same hardware instance.

The operation fails when the netdev is an upper of netdevs with
different parent identifiers.

Instead of failing the enslavement, have dev_get_port_parent_id() return
'-EOPNOTSUPP' which will signal the bridge to skip the query operation.
Other callers of the function are not affected by this change.

Fixes: 7e1146e8c10c ("net: devlink: introduce devlink_compat_switch_id_get() helper")
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reported-by: Vasundhara Volam &lt;vasundhara-v.volam@broadcom.com&gt;
Reviewed-by: Jiri Pirko &lt;jiri@nvidia.com&gt;
Reviewed-by: Nikolay Aleksandrov &lt;nikolay@nvidia.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: disable netpoll on fresh napis</title>
<updated>2020-09-12T12:18:55Z</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2020-08-26T19:40:06Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=ddb279d64b724b197dec829c016b5d386314b970'/>
<id>urn:sha1:ddb279d64b724b197dec829c016b5d386314b970</id>
<content type='text'>
[ Upstream commit 96e97bc07e90f175a8980a22827faf702ca4cb30 ]

napi_disable() makes sure to set the NAPI_STATE_NPSVC bit to prevent
netpoll from accessing rings before init is complete. However, the
same is not done for fresh napi instances in netif_napi_add(),
even though we expect NAPI instances to be added as disabled.

This causes crashes during driver reconfiguration (enabling XDP,
changing the channel count) - if there is any printk() after
netif_napi_add() but before napi_enable().

To ensure memory ordering is correct we need to use RCU accessors.

Reported-by: Rob Sherwood &lt;rsher@fb.com&gt;
Fixes: 2d8bff12699a ("netpoll: Close race condition between poll_one_napi and napi_disable")
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: core: use listified Rx for GRO_NORMAL in napi_gro_receive()</title>
<updated>2020-09-09T17:12:31Z</updated>
<author>
<name>Alexander Lobakin</name>
<email>alobakin@dlink.ru</email>
</author>
<published>2019-10-14T08:00:33Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=de53545e8d4c145773da033b331581b7cbcc15da'/>
<id>urn:sha1:de53545e8d4c145773da033b331581b7cbcc15da</id>
<content type='text'>
commit 6570bc79c0dfff0f228b7afd2de720fb4e84d61d upstream.

Commit 323ebb61e32b4 ("net: use listified RX for handling GRO_NORMAL
skbs") made use of listified skb processing for the users of
napi_gro_frags().
The same technique can be used in a way more common napi_gro_receive()
to speed up non-merged (GRO_NORMAL) skbs for a wide range of drivers
including gro_cells and mac80211 users.
This slightly changes the return value in cases where skb is being
dropped by the core stack, but it seems to have no impact on related
drivers' functionality.
gro_normal_batch is left untouched as it's very individual for every
single system configuration and might be tuned in manual order to
achieve an optimal performance.

Signed-off-by: Alexander Lobakin &lt;alobakin@dlink.ru&gt;
Acked-by: Edward Cree &lt;ecree@solarflare.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Hyunsoon Kim &lt;h10.kim@samsung.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>dev: Defer free of skbs in flush_backlog</title>
<updated>2020-07-31T16:39:30Z</updated>
<author>
<name>Subash Abhinov Kasiviswanathan</name>
<email>subashab@codeaurora.org</email>
</author>
<published>2020-07-23T17:31:48Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=d109acd58052ce4affc01e931765045c368ed31e'/>
<id>urn:sha1:d109acd58052ce4affc01e931765045c368ed31e</id>
<content type='text'>
[ Upstream commit 7df5cb75cfb8acf96c7f2342530eb41e0c11f4c3 ]

IRQs are disabled when freeing skbs in input queue.
Use the IRQ safe variant to free skbs here.

Fixes: 145dd5f9c88f ("net: flush the softnet backlog in process context")
Signed-off-by: Subash Abhinov Kasiviswanathan &lt;subashab@codeaurora.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: increment xmit_recursion level in dev_direct_xmit()</title>
<updated>2020-06-30T19:36:44Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2020-06-18T05:23:25Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=67571b1ab2963dca6a031a08b785a1bc7c214433'/>
<id>urn:sha1:67571b1ab2963dca6a031a08b785a1bc7c214433</id>
<content type='text'>
[ Upstream commit 0ad6f6e767ec2f613418cbc7ebe5ec4c35af540c ]

Back in commit f60e5990d9c1 ("ipv6: protect skb-&gt;sk accesses
from recursive dereference inside the stack") Hannes added code
so that IPv6 stack would not trust skb-&gt;sk for typical cases
where packet goes through 'standard' xmit path (__dev_queue_xmit())

Alas af_packet had a dev_direct_xmit() path that was not
dealing yet with xmit_recursion level.

Also change sk_mc_loop() to dump a stack once only.

Without this patch, syzbot was able to trigger :

[1]
[  153.567378] WARNING: CPU: 7 PID: 11273 at net/core/sock.c:721 sk_mc_loop+0x51/0x70
[  153.567378] Modules linked in: nfnetlink ip6table_raw ip6table_filter iptable_raw iptable_nat nf_nat nf_conntrack nf_defrag_ipv4 nf_defrag_ipv6 iptable_filter macsec macvtap tap macvlan 8021q hsr wireguard libblake2s blake2s_x86_64 libblake2s_generic udp_tunnel ip6_udp_tunnel libchacha20poly1305 poly1305_x86_64 chacha_x86_64 libchacha curve25519_x86_64 libcurve25519_generic netdevsim batman_adv dummy team bridge stp llc w1_therm wire i2c_mux_pca954x i2c_mux cdc_acm ehci_pci ehci_hcd mlx4_en mlx4_ib ib_uverbs ib_core mlx4_core
[  153.567386] CPU: 7 PID: 11273 Comm: b159172088 Not tainted 5.8.0-smp-DEV #273
[  153.567387] RIP: 0010:sk_mc_loop+0x51/0x70
[  153.567388] Code: 66 83 f8 0a 75 24 0f b6 4f 12 b8 01 00 00 00 31 d2 d3 e0 a9 bf ef ff ff 74 07 48 8b 97 f0 02 00 00 0f b6 42 3a 83 e0 01 5d c3 &lt;0f&gt; 0b b8 01 00 00 00 5d c3 0f b6 87 18 03 00 00 5d c0 e8 04 83 e0
[  153.567388] RSP: 0018:ffff95c69bb93990 EFLAGS: 00010212
[  153.567388] RAX: 0000000000000011 RBX: ffff95c6e0ee3e00 RCX: 0000000000000007
[  153.567389] RDX: ffff95c69ae50000 RSI: ffff95c6c30c3000 RDI: ffff95c6c30c3000
[  153.567389] RBP: ffff95c69bb93990 R08: ffff95c69a77f000 R09: 0000000000000008
[  153.567389] R10: 0000000000000040 R11: 00003e0e00026128 R12: ffff95c6c30c3000
[  153.567390] R13: ffff95c6cc4fd500 R14: ffff95c6f84500c0 R15: ffff95c69aa13c00
[  153.567390] FS:  00007fdc3a283700(0000) GS:ffff95c6ff9c0000(0000) knlGS:0000000000000000
[  153.567390] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  153.567391] CR2: 00007ffee758e890 CR3: 0000001f9ba20003 CR4: 00000000001606e0
[  153.567391] Call Trace:
[  153.567391]  ip6_finish_output2+0x34e/0x550
[  153.567391]  __ip6_finish_output+0xe7/0x110
[  153.567391]  ip6_finish_output+0x2d/0xb0
[  153.567392]  ip6_output+0x77/0x120
[  153.567392]  ? __ip6_finish_output+0x110/0x110
[  153.567392]  ip6_local_out+0x3d/0x50
[  153.567392]  ipvlan_queue_xmit+0x56c/0x5e0
[  153.567393]  ? ksize+0x19/0x30
[  153.567393]  ipvlan_start_xmit+0x18/0x50
[  153.567393]  dev_direct_xmit+0xf3/0x1c0
[  153.567393]  packet_direct_xmit+0x69/0xa0
[  153.567394]  packet_sendmsg+0xbf0/0x19b0
[  153.567394]  ? plist_del+0x62/0xb0
[  153.567394]  sock_sendmsg+0x65/0x70
[  153.567394]  sock_write_iter+0x93/0xf0
[  153.567394]  new_sync_write+0x18e/0x1a0
[  153.567395]  __vfs_write+0x29/0x40
[  153.567395]  vfs_write+0xb9/0x1b0
[  153.567395]  ksys_write+0xb1/0xe0
[  153.567395]  __x64_sys_write+0x1a/0x20
[  153.567395]  do_syscall_64+0x43/0x70
[  153.567396]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  153.567396] RIP: 0033:0x453549
[  153.567396] Code: Bad RIP value.
[  153.567396] RSP: 002b:00007fdc3a282cc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  153.567397] RAX: ffffffffffffffda RBX: 00000000004d32d0 RCX: 0000000000453549
[  153.567397] RDX: 0000000000000020 RSI: 0000000020000300 RDI: 0000000000000003
[  153.567398] RBP: 00000000004d32d8 R08: 0000000000000000 R09: 0000000000000000
[  153.567398] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004d32dc
[  153.567398] R13: 00007ffee742260f R14: 00007fdc3a282dc0 R15: 00007fdc3a283700
[  153.567399] ---[ end trace c1d5ae2b1059ec62 ]---

f60e5990d9c1 ("ipv6: protect skb-&gt;sk accesses from recursive dereference inside the stack")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: fix memleak in register_netdevice()</title>
<updated>2020-06-30T19:36:44Z</updated>
<author>
<name>Yang Yingliang</name>
<email>yangyingliang@huawei.com</email>
</author>
<published>2020-06-16T09:39:21Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=742f2358b3248832bf46745e5bd7a06dfa3aae53'/>
<id>urn:sha1:742f2358b3248832bf46745e5bd7a06dfa3aae53</id>
<content type='text'>
[ Upstream commit 814152a89ed52c722ab92e9fbabcac3cb8a39245 ]

I got a memleak report when doing some fuzz test:

unreferenced object 0xffff888112584000 (size 13599):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 32 bytes):
    74 61 70 30 00 00 00 00 00 00 00 00 00 00 00 00  tap0............
    00 ee d9 19 81 88 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [&lt;000000002f60ba65&gt;] __kmalloc_node+0x309/0x3a0
    [&lt;0000000075b211ec&gt;] kvmalloc_node+0x7f/0xc0
    [&lt;00000000d3a97396&gt;] alloc_netdev_mqs+0x76/0xfc0
    [&lt;00000000609c3655&gt;] __tun_chr_ioctl+0x1456/0x3d70
    [&lt;000000001127ca24&gt;] ksys_ioctl+0xe5/0x130
    [&lt;00000000b7d5e66a&gt;] __x64_sys_ioctl+0x6f/0xb0
    [&lt;00000000e1023498&gt;] do_syscall_64+0x56/0xa0
    [&lt;000000009ec0eb12&gt;] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff888111845cc0 (size 8):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 8 bytes):
    74 61 70 30 00 88 ff ff                          tap0....
  backtrace:
    [&lt;000000004c159777&gt;] kstrdup+0x35/0x70
    [&lt;00000000d8b496ad&gt;] kstrdup_const+0x3d/0x50
    [&lt;00000000494e884a&gt;] kvasprintf_const+0xf1/0x180
    [&lt;0000000097880a2b&gt;] kobject_set_name_vargs+0x56/0x140
    [&lt;000000008fbdfc7b&gt;] dev_set_name+0xab/0xe0
    [&lt;000000005b99e3b4&gt;] netdev_register_kobject+0xc0/0x390
    [&lt;00000000602704fe&gt;] register_netdevice+0xb61/0x1250
    [&lt;000000002b7ca244&gt;] __tun_chr_ioctl+0x1cd1/0x3d70
    [&lt;000000001127ca24&gt;] ksys_ioctl+0xe5/0x130
    [&lt;00000000b7d5e66a&gt;] __x64_sys_ioctl+0x6f/0xb0
    [&lt;00000000e1023498&gt;] do_syscall_64+0x56/0xa0
    [&lt;000000009ec0eb12&gt;] entry_SYSCALL_64_after_hwframe+0x44/0xa9
unreferenced object 0xffff88811886d800 (size 512):
  comm "ip", pid 3048, jiffies 4294911734 (age 343.491s)
  hex dump (first 32 bytes):
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
    ff ff ff ff ff ff ff ff c0 66 3d a3 ff ff ff ff  .........f=.....
  backtrace:
    [&lt;0000000050315800&gt;] device_add+0x61e/0x1950
    [&lt;0000000021008dfb&gt;] netdev_register_kobject+0x17e/0x390
    [&lt;00000000602704fe&gt;] register_netdevice+0xb61/0x1250
    [&lt;000000002b7ca244&gt;] __tun_chr_ioctl+0x1cd1/0x3d70
    [&lt;000000001127ca24&gt;] ksys_ioctl+0xe5/0x130
    [&lt;00000000b7d5e66a&gt;] __x64_sys_ioctl+0x6f/0xb0
    [&lt;00000000e1023498&gt;] do_syscall_64+0x56/0xa0
    [&lt;000000009ec0eb12&gt;] entry_SYSCALL_64_after_hwframe+0x44/0xa9

If call_netdevice_notifiers() failed, then rollback_registered()
calls netdev_unregister_kobject() which holds the kobject. The
reference cannot be put because the netdev won't be add to todo
list, so it will leads a memleak, we need put the reference to
avoid memleak.

Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Yang Yingliang &lt;yangyingliang@huawei.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
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