<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/net/caif, branch v6.16</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>rtnetlink: Pack newlink() params into struct</title>
<updated>2025-02-21T23:28:02+00:00</updated>
<author>
<name>Xiao Liang</name>
<email>shaw.leon@gmail.com</email>
</author>
<published>2025-02-19T12:50:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=69c7be1b903fca2835e80ec506bd1d75ce84fb4d'/>
<id>69c7be1b903fca2835e80ec506bd1d75ce84fb4d</id>
<content type='text'>
There are 4 net namespaces involved when creating links:

 - source netns - where the netlink socket resides,
 - target netns - where to put the device being created,
 - link netns - netns associated with the device (backend),
 - peer netns - netns of peer device.

Currently, two nets are passed to newlink() callback - "src_net"
parameter and "dev_net" (implicitly in net_device). They are set as
follows, depending on netlink attributes in the request.

 +------------+-------------------+---------+---------+
 | peer netns | IFLA_LINK_NETNSID | src_net | dev_net |
 +------------+-------------------+---------+---------+
 |            | absent            | source  | target  |
 | absent     +-------------------+---------+---------+
 |            | present           | link    | link    |
 +------------+-------------------+---------+---------+
 |            | absent            | peer    | target  |
 | present    +-------------------+---------+---------+
 |            | present           | peer    | link    |
 +------------+-------------------+---------+---------+

When IFLA_LINK_NETNSID is present, the device is created in link netns
first and then moved to target netns. This has some side effects,
including extra ifindex allocation, ifname validation and link events.
These could be avoided if we create it in target netns from
the beginning.

On the other hand, the meaning of src_net parameter is ambiguous. It
varies depending on how parameters are passed. It is the effective
link (or peer netns) by design, but some drivers ignore it and use
dev_net instead.

To provide more netns context for drivers, this patch packs existing
newlink() parameters, along with the source netns, link netns and peer
netns, into a struct. The old "src_net" is renamed to "net" to avoid
confusion with real source netns, and will be deprecated later. The use
of src_net are converted to params-&gt;net trivially.

Signed-off-by: Xiao Liang &lt;shaw.leon@gmail.com&gt;
Reviewed-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20250219125039.18024-3-shaw.leon@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There are 4 net namespaces involved when creating links:

 - source netns - where the netlink socket resides,
 - target netns - where to put the device being created,
 - link netns - netns associated with the device (backend),
 - peer netns - netns of peer device.

Currently, two nets are passed to newlink() callback - "src_net"
parameter and "dev_net" (implicitly in net_device). They are set as
follows, depending on netlink attributes in the request.

 +------------+-------------------+---------+---------+
 | peer netns | IFLA_LINK_NETNSID | src_net | dev_net |
 +------------+-------------------+---------+---------+
 |            | absent            | source  | target  |
 | absent     +-------------------+---------+---------+
 |            | present           | link    | link    |
 +------------+-------------------+---------+---------+
 |            | absent            | peer    | target  |
 | present    +-------------------+---------+---------+
 |            | present           | peer    | link    |
 +------------+-------------------+---------+---------+

When IFLA_LINK_NETNSID is present, the device is created in link netns
first and then moved to target netns. This has some side effects,
including extra ifindex allocation, ifname validation and link events.
These could be avoided if we create it in target netns from
the beginning.

On the other hand, the meaning of src_net parameter is ambiguous. It
varies depending on how parameters are passed. It is the effective
link (or peer netns) by design, but some drivers ignore it and use
dev_net instead.

To provide more netns context for drivers, this patch packs existing
newlink() parameters, along with the source netns, link netns and peer
netns, into a struct. The old "src_net" is renamed to "net" to avoid
confusion with real source netns, and will be deprecated later. The use
of src_net are converted to params-&gt;net trivially.

Signed-off-by: Xiao Liang &lt;shaw.leon@gmail.com&gt;
Reviewed-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20250219125039.18024-3-shaw.leon@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>caif: Remove unused cfsrvl_getphyid</title>
<updated>2024-10-08T22:33:49+00:00</updated>
<author>
<name>Dr. David Alan Gilbert</name>
<email>linux@treblig.org</email>
</author>
<published>2024-10-07T00:44:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3fe3dbaf26723c473d42a58b636a2500586b821e'/>
<id>3fe3dbaf26723c473d42a58b636a2500586b821e</id>
<content type='text'>
cfsrvl_getphyid() has been unused since 2011's commit
f36214408470 ("caif: Use RCU and lists in cfcnfg.c for managing caif link layers")

Remove it.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20241007004456.149899-1-linux@treblig.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
cfsrvl_getphyid() has been unused since 2011's commit
f36214408470 ("caif: Use RCU and lists in cfcnfg.c for managing caif link layers")

Remove it.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20241007004456.149899-1-linux@treblig.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>move asm/unaligned.h to linux/unaligned.h</title>
<updated>2024-10-02T21:23:23+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2024-10-01T19:35:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5f60d5f6bbc12e782fac78110b0ee62698f3b576'/>
<id>5f60d5f6bbc12e782fac78110b0ee62698f3b576</id>
<content type='text'>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.

auto-generated by the following:

for i in `git grep -l -w asm/unaligned.h`; do
	sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
	sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
asm/unaligned.h is always an include of asm-generic/unaligned.h;
might as well move that thing to linux/unaligned.h and include
that - there's nothing arch-specific in that header.

auto-generated by the following:

for i in `git grep -l -w asm/unaligned.h`; do
	sed -i -e "s/asm\/unaligned.h/linux\/unaligned.h/" $i
done
for i in `git grep -l -w asm-generic/unaligned.h`; do
	sed -i -e "s/asm-generic\/unaligned.h/linux\/unaligned.h/" $i
done
git mv include/asm-generic/unaligned.h include/linux/unaligned.h
git mv tools/include/asm-generic/unaligned.h tools/include/linux/unaligned.h
sed -i -e "/unaligned.h/d" include/asm-generic/Kbuild
sed -i -e "s/__ASM_GENERIC/__LINUX/" include/linux/unaligned.h tools/include/linux/unaligned.h
</pre>
</div>
</content>
</entry>
<entry>
<title>net: caif: remove unused name</title>
<updated>2024-09-13T03:29:04+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2024-09-11T01:52:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5905c024a776c7f592581551993817aaf0cd1f36'/>
<id>5905c024a776c7f592581551993817aaf0cd1f36</id>
<content type='text'>
Justin sent a patch to use strscpy_pad() instead of strncpy()
on the name field. Simon rightly asked why the _pad() version
is used, and looking closer name seems completely unused,
the last code which referred to it was removed in
commit 8391c4aab1aa ("caif: Bugfixes in CAIF netdevice for close and flow control")

Link: https://lore.kernel.org/20240909-strncpy-net-caif-chnl_net-c-v1-1-438eb870c155@google.com
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Acked-by: Justin Stitt &lt;justinstitt@google.com&gt;
Link: https://patch.msgid.link/20240911015228.1555779-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Justin sent a patch to use strscpy_pad() instead of strncpy()
on the name field. Simon rightly asked why the _pad() version
is used, and looking closer name seems completely unused,
the last code which referred to it was removed in
commit 8391c4aab1aa ("caif: Bugfixes in CAIF netdevice for close and flow control")

Link: https://lore.kernel.org/20240909-strncpy-net-caif-chnl_net-c-v1-1-438eb870c155@google.com
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Acked-by: Justin Stitt &lt;justinstitt@google.com&gt;
Link: https://patch.msgid.link/20240911015228.1555779-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: caif: use max() to simplify the code</title>
<updated>2024-08-26T16:48:53+00:00</updated>
<author>
<name>Li Zetao</name>
<email>lizetao1@huawei.com</email>
</author>
<published>2024-08-22T13:39:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b4985aa8e312fd40fbbce0fe44ce677368fdee43'/>
<id>b4985aa8e312fd40fbbce0fe44ce677368fdee43</id>
<content type='text'>
When processing the tail append of sk buffer, the final length needs
to be determined based on expectlen and addlen. Using max() here can
increase the readability of the code.

Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20240822133908.1042240-4-lizetao1@huawei.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When processing the tail append of sk buffer, the final length needs
to be determined based on expectlen and addlen. Using max() here can
increase the readability of the code.

Signed-off-by: Li Zetao &lt;lizetao1@huawei.com&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20240822133908.1042240-4-lizetao1@huawei.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: caif: remove unused structs</title>
<updated>2024-06-05T09:18:06+00:00</updated>
<author>
<name>Dr. David Alan Gilbert</name>
<email>linux@treblig.org</email>
</author>
<published>2024-05-31T23:29:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6f49c3fb563c0a95a838216eaf7d9b02ece44bf5'/>
<id>6f49c3fb563c0a95a838216eaf7d9b02ece44bf5</id>
<content type='text'>
'cfpktq' has been unused since
commit 73d6ac633c6c ("caif: code cleanup").

'caif_packet_funcs' is declared but never defined.

Remove both of them.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Reviewed-by: Jacob Keller &lt;jacob.e.keller@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
'cfpktq' has been unused since
commit 73d6ac633c6c ("caif: code cleanup").

'caif_packet_funcs' is declared but never defined.

Remove both of them.

Signed-off-by: Dr. David Alan Gilbert &lt;linux@treblig.org&gt;
Reviewed-by: Jacob Keller &lt;jacob.e.keller@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>caif: Use UTILITY_NAME_LENGTH instead of hard-coding 16</title>
<updated>2024-04-03T01:20:00+00:00</updated>
<author>
<name>Christophe JAILLET</name>
<email>christophe.jaillet@wanadoo.fr</email>
</author>
<published>2024-03-30T08:32:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f9a4506438a1068d9ff613319bc64dcaa65f681d'/>
<id>f9a4506438a1068d9ff613319bc64dcaa65f681d</id>
<content type='text'>
UTILITY_NAME_LENGTH is 16. So better use the former when defining the
'utility_name' array. This makes the intent clearer when it is used around
line 260.

While at it, declare variable in reverse xmas tree style.

Signed-off-by: Christophe JAILLET &lt;christophe.jaillet@wanadoo.fr&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://lore.kernel.org/r/8c1160501f69b64bb2d45ce9f26f746eec80ac77.1711787352.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
UTILITY_NAME_LENGTH is 16. So better use the former when defining the
'utility_name' array. This makes the intent clearer when it is used around
line 260.

While at it, declare variable in reverse xmas tree style.

Signed-off-by: Christophe JAILLET &lt;christophe.jaillet@wanadoo.fr&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://lore.kernel.org/r/8c1160501f69b64bb2d45ce9f26f746eec80ac77.1711787352.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: fill in MODULE_DESCRIPTION()s for CAIF</title>
<updated>2024-01-05T16:06:35+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2024-01-04T14:48:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cb420106901ad038ea8b3c58fe26a5a465c40080'/>
<id>cb420106901ad038ea8b3c58fe26a5a465c40080</id>
<content type='text'>
W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to all the CAIF sub-modules.

Link: https://lore.kernel.org/r/20240104144855.1320993-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to all the CAIF sub-modules.

Link: https://lore.kernel.org/r/20240104144855.1320993-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sock: Remove -&gt;sendpage*() in favour of sendmsg(MSG_SPLICE_PAGES)</title>
<updated>2023-06-24T22:50:13+00:00</updated>
<author>
<name>David Howells</name>
<email>dhowells@redhat.com</email>
</author>
<published>2023-06-23T22:55:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=dc97391e661009eab46783030d2404c9b6e6f2e7'/>
<id>dc97391e661009eab46783030d2404c9b6e6f2e7</id>
<content type='text'>
Remove -&gt;sendpage() and -&gt;sendpage_locked().  sendmsg() with
MSG_SPLICE_PAGES should be used instead.  This allows multiple pages and
multipage folios to be passed through.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Acked-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt; # for net/can
cc: Jens Axboe &lt;axboe@kernel.dk&gt;
cc: Matthew Wilcox &lt;willy@infradead.org&gt;
cc: linux-afs@lists.infradead.org
cc: mptcp@lists.linux.dev
cc: rds-devel@oss.oracle.com
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
Link: https://lore.kernel.org/r/20230623225513.2732256-16-dhowells@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Remove -&gt;sendpage() and -&gt;sendpage_locked().  sendmsg() with
MSG_SPLICE_PAGES should be used instead.  This allows multiple pages and
multipage folios to be passed through.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Acked-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt; # for net/can
cc: Jens Axboe &lt;axboe@kernel.dk&gt;
cc: Matthew Wilcox &lt;willy@infradead.org&gt;
cc: linux-afs@lists.infradead.org
cc: mptcp@lists.linux.dev
cc: rds-devel@oss.oracle.com
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
Link: https://lore.kernel.org/r/20230623225513.2732256-16-dhowells@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: caif: Fix use-after-free in cfusbl_device_notify()</title>
<updated>2023-03-03T06:22:07+00:00</updated>
<author>
<name>Shigeru Yoshida</name>
<email>syoshida@redhat.com</email>
</author>
<published>2023-03-01T16:39:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9781e98a97110f5e76999058368b4be76a788484'/>
<id>9781e98a97110f5e76999058368b4be76a788484</id>
<content type='text'>
syzbot reported use-after-free in cfusbl_device_notify() [1].  This
causes a stack trace like below:

BUG: KASAN: use-after-free in cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
Read of size 8 at addr ffff88807ac4e6f0 by task kworker/u4:6/1214

CPU: 0 PID: 1214 Comm: kworker/u4:6 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 &lt;TASK&gt;
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
 print_report mm/kasan/report.c:429 [inline]
 kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
 cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945
 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
 call_netdevice_notifiers net/core/dev.c:1997 [inline]
 netdev_wait_allrefs_any net/core/dev.c:10227 [inline]
 netdev_run_todo+0xbc0/0x10f0 net/core/dev.c:10341
 default_device_exit_batch+0x44e/0x590 net/core/dev.c:11334
 ops_exit_list+0x125/0x170 net/core/net_namespace.c:167
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
 &lt;/TASK&gt;

When unregistering a net device, unregister_netdevice_many_notify()
sets the device's reg_state to NETREG_UNREGISTERING, calls notifiers
with NETDEV_UNREGISTER, and adds the device to the todo list.

Later on, devices in the todo list are processed by netdev_run_todo().
netdev_run_todo() waits devices' reference count become 1 while
rebdoadcasting NETDEV_UNREGISTER notification.

When cfusbl_device_notify() is called with NETDEV_UNREGISTER multiple
times, the parent device might be freed.  This could cause UAF.
Processing NETDEV_UNREGISTER multiple times also causes inbalance of
reference count for the module.

This patch fixes the issue by accepting only first NETDEV_UNREGISTER
notification.

Fixes: 7ad65bf68d70 ("caif: Add support for CAIF over CDC NCM USB interface")
CC: sjur.brandeland@stericsson.com &lt;sjur.brandeland@stericsson.com&gt;
Reported-by: syzbot+b563d33852b893653a9e@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=c3bfd8e2450adab3bffe4d80821fbbced600407f [1]
Signed-off-by: Shigeru Yoshida &lt;syoshida@redhat.com&gt;
Link: https://lore.kernel.org/r/20230301163913.391304-1-syoshida@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
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syzbot reported use-after-free in cfusbl_device_notify() [1].  This
causes a stack trace like below:

BUG: KASAN: use-after-free in cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
Read of size 8 at addr ffff88807ac4e6f0 by task kworker/u4:6/1214

CPU: 0 PID: 1214 Comm: kworker/u4:6 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 &lt;TASK&gt;
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
 print_report mm/kasan/report.c:429 [inline]
 kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
 cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945
 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
 call_netdevice_notifiers net/core/dev.c:1997 [inline]
 netdev_wait_allrefs_any net/core/dev.c:10227 [inline]
 netdev_run_todo+0xbc0/0x10f0 net/core/dev.c:10341
 default_device_exit_batch+0x44e/0x590 net/core/dev.c:11334
 ops_exit_list+0x125/0x170 net/core/net_namespace.c:167
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
 &lt;/TASK&gt;

When unregistering a net device, unregister_netdevice_many_notify()
sets the device's reg_state to NETREG_UNREGISTERING, calls notifiers
with NETDEV_UNREGISTER, and adds the device to the todo list.

Later on, devices in the todo list are processed by netdev_run_todo().
netdev_run_todo() waits devices' reference count become 1 while
rebdoadcasting NETDEV_UNREGISTER notification.

When cfusbl_device_notify() is called with NETDEV_UNREGISTER multiple
times, the parent device might be freed.  This could cause UAF.
Processing NETDEV_UNREGISTER multiple times also causes inbalance of
reference count for the module.

This patch fixes the issue by accepting only first NETDEV_UNREGISTER
notification.

Fixes: 7ad65bf68d70 ("caif: Add support for CAIF over CDC NCM USB interface")
CC: sjur.brandeland@stericsson.com &lt;sjur.brandeland@stericsson.com&gt;
Reported-by: syzbot+b563d33852b893653a9e@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=c3bfd8e2450adab3bffe4d80821fbbced600407f [1]
Signed-off-by: Shigeru Yoshida &lt;syoshida@redhat.com&gt;
Link: https://lore.kernel.org/r/20230301163913.391304-1-syoshida@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
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