In the Linux kernel, the following vulnerability has been resolved:
amt: Don't support cross-netns setup.
When a lower device is unregistered, amt_device_event() tries
to unregister its upper AMT device, but it has two problems.
1. amt_lookup_upper_dev() looks up an upper device in the
lower device's netns only
2. amt_device_event() unregisters a single upper device only
If AMT device is created on a lower device in another netns,
removing the lower device triggers the splat below and gets
stuck until all upper devices are removed. [0]
The cross-netns setup seems unintentional considering 1. and
the following points:
* amt_link_setup() sets dev->netns_immutable to true
* skb_scrub_packet() is not called in the fast path
* iproute2 binary fails to find cross-netns lower device via
link-netns:
# ip -n ns1 link add amt0 link-netns ns2 type amt dev veth1
Cannot find device "veth1"
Instead of supporting it properly and preparing for per-netns
netdev unreg, let's forbid cross-netns setup.
Note that the problem 2. needs a separate fix.
[0]:
WARNING: net/core/dev.c:12518 at unregister_netdevice_many_notify+0x1cce/0x2250, CPU#48: ip/2031
Modules linked in:
CPU: 48 UID: 0 PID: 2031 Comm: ip Not tainted 7.2.0-rc5+ #27 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:12518)
Code: 89 ef e8 d5 52 ae fe e9 d0 f4 ff ff 48 8d 3d f9 3b 9c 02 48 c7 c6 c0 0b 63 84 ba ab 1f 00 00 67 48 0f b9 3a e9 65 ff ff ff 90 <0f> 0b 90 eb 81 48 8d 3d f6 3b 9c 02 48 c7 c6 c0 0b 63 84 ba e2 1f
RSP: 0018:ffffc90004abf160 EFLAGS: 00010212
RAX: ffff888104d38260 RBX: ffff88800b0911b8 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff85b9f880
RBP: ffffc90004abf2d0 R08: ffffffff85b9f887 R09: 1ffffffff0b73f10
R10: dffffc0000000000 R11: fffffbfff0b73f11 R12: ffff88800b091d08
R13: ffff88800b091178 R14: dffffc0000000000 R15: ffff88800b091000
FS: 00007f555b86c600(0000) GS:ffff8881942a0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562107d489c0 CR3: 0000000109a40002 CR4: 0000000000372ef0
Call Trace:
<TASK>
rtnl_dellink (net/core/rtnetlink.c:3632 net/core/rtnetlink.c:3674)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7112)
netlink_rcv_skb (net/netlink/af_netlink.c:2556)
netlink_unicast (net/netlink/af_netlink.c:1319)
netlink_sendmsg (net/netlink/af_netlink.c:1900)
____sys_sendmsg (net/socket.c:775)
__sys_sendmsg (net/socket.c:2738)
do_syscall_64 (arch/x86/entry/syscall_64.c:63)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
...
unregister_netdevice: waiting for veth0 to become free. Usage count = 7
ref_tracker: netdev@ffff88800d7496d8 has 3/3 users at
__netdev_adjacent_dev_insert (./include/linux/netdevice.h:4525 ./include/linux/netdevice.h:4554 net/core/dev.c:8791)
__netdev_upper_dev_link (net/core/dev.c:8879 net/core/dev.c:8963)
netdev_upper_dev_link (net/core/dev.c:9009)
amt_newlink (drivers/net/amt.c:3321)
amt: Don't support cross-netns setup.
When a lower device is unregistered, amt_device_event() tries
to unregister its upper AMT device, but it has two problems.
1. amt_lookup_upper_dev() looks up an upper device in the
lower device's netns only
2. amt_device_event() unregisters a single upper device only
If AMT device is created on a lower device in another netns,
removing the lower device triggers the splat below and gets
stuck until all upper devices are removed. [0]
The cross-netns setup seems unintentional considering 1. and
the following points:
* amt_link_setup() sets dev->netns_immutable to true
* skb_scrub_packet() is not called in the fast path
* iproute2 binary fails to find cross-netns lower device via
link-netns:
# ip -n ns1 link add amt0 link-netns ns2 type amt dev veth1
Cannot find device "veth1"
Instead of supporting it properly and preparing for per-netns
netdev unreg, let's forbid cross-netns setup.
Note that the problem 2. needs a separate fix.
[0]:
WARNING: net/core/dev.c:12518 at unregister_netdevice_many_notify+0x1cce/0x2250, CPU#48: ip/2031
Modules linked in:
CPU: 48 UID: 0 PID: 2031 Comm: ip Not tainted 7.2.0-rc5+ #27 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:12518)
Code: 89 ef e8 d5 52 ae fe e9 d0 f4 ff ff 48 8d 3d f9 3b 9c 02 48 c7 c6 c0 0b 63 84 ba ab 1f 00 00 67 48 0f b9 3a e9 65 ff ff ff 90 <0f> 0b 90 eb 81 48 8d 3d f6 3b 9c 02 48 c7 c6 c0 0b 63 84 ba e2 1f
RSP: 0018:ffffc90004abf160 EFLAGS: 00010212
RAX: ffff888104d38260 RBX: ffff88800b0911b8 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff85b9f880
RBP: ffffc90004abf2d0 R08: ffffffff85b9f887 R09: 1ffffffff0b73f10
R10: dffffc0000000000 R11: fffffbfff0b73f11 R12: ffff88800b091d08
R13: ffff88800b091178 R14: dffffc0000000000 R15: ffff88800b091000
FS: 00007f555b86c600(0000) GS:ffff8881942a0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562107d489c0 CR3: 0000000109a40002 CR4: 0000000000372ef0
Call Trace:
<TASK>
rtnl_dellink (net/core/rtnetlink.c:3632 net/core/rtnetlink.c:3674)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7112)
netlink_rcv_skb (net/netlink/af_netlink.c:2556)
netlink_unicast (net/netlink/af_netlink.c:1319)
netlink_sendmsg (net/netlink/af_netlink.c:1900)
____sys_sendmsg (net/socket.c:775)
__sys_sendmsg (net/socket.c:2738)
do_syscall_64 (arch/x86/entry/syscall_64.c:63)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
...
unregister_netdevice: waiting for veth0 to become free. Usage count = 7
ref_tracker: netdev@ffff88800d7496d8 has 3/3 users at
__netdev_adjacent_dev_insert (./include/linux/netdevice.h:4525 ./include/linux/netdevice.h:4554 net/core/dev.c:8791)
__netdev_upper_dev_link (net/core/dev.c:8879 net/core/dev.c:8963)
netdev_upper_dev_link (net/core/dev.c:9009)
amt_newlink (drivers/net/amt.c:3321)
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
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Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: amt: Don't support cross-netns setup. When a lower device is unregistered, amt_device_event() tries to unregister its upper AMT device, but it has two problems. 1. amt_lookup_upper_dev() looks up an upper device in the lower device's netns only 2. amt_device_event() unregisters a single upper device only If AMT device is created on a lower device in another netns, removing the lower device triggers the splat below and gets stuck until all upper devices are removed. [0] The cross-netns setup seems unintentional considering 1. and the following points: * amt_link_setup() sets dev->netns_immutable to true * skb_scrub_packet() is not called in the fast path * iproute2 binary fails to find cross-netns lower device via link-netns: # ip -n ns1 link add amt0 link-netns ns2 type amt dev veth1 Cannot find device "veth1" Instead of supporting it properly and preparing for per-netns netdev unreg, let's forbid cross-netns setup. Note that the problem 2. needs a separate fix. [0]: WARNING: net/core/dev.c:12518 at unregister_netdevice_many_notify+0x1cce/0x2250, CPU#48: ip/2031 Modules linked in: CPU: 48 UID: 0 PID: 2031 Comm: ip Not tainted 7.2.0-rc5+ #27 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:12518) Code: 89 ef e8 d5 52 ae fe e9 d0 f4 ff ff 48 8d 3d f9 3b 9c 02 48 c7 c6 c0 0b 63 84 ba ab 1f 00 00 67 48 0f b9 3a e9 65 ff ff ff 90 <0f> 0b 90 eb 81 48 8d 3d f6 3b 9c 02 48 c7 c6 c0 0b 63 84 ba e2 1f RSP: 0018:ffffc90004abf160 EFLAGS: 00010212 RAX: ffff888104d38260 RBX: ffff88800b0911b8 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff85b9f880 RBP: ffffc90004abf2d0 R08: ffffffff85b9f887 R09: 1ffffffff0b73f10 R10: dffffc0000000000 R11: fffffbfff0b73f11 R12: ffff88800b091d08 R13: ffff88800b091178 R14: dffffc0000000000 R15: ffff88800b091000 FS: 00007f555b86c600(0000) GS:ffff8881942a0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562107d489c0 CR3: 0000000109a40002 CR4: 0000000000372ef0 Call Trace: <TASK> rtnl_dellink (net/core/rtnetlink.c:3632 net/core/rtnetlink.c:3674) rtnetlink_rcv_msg (net/core/rtnetlink.c:7112) netlink_rcv_skb (net/netlink/af_netlink.c:2556) netlink_unicast (net/netlink/af_netlink.c:1319) netlink_sendmsg (net/netlink/af_netlink.c:1900) ____sys_sendmsg (net/socket.c:775) __sys_sendmsg (net/socket.c:2738) do_syscall_64 (arch/x86/entry/syscall_64.c:63) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) ... unregister_netdevice: waiting for veth0 to become free. Usage count = 7 ref_tracker: netdev@ffff88800d7496d8 has 3/3 users at __netdev_adjacent_dev_insert (./include/linux/netdevice.h:4525 ./include/linux/netdevice.h:4554 net/core/dev.c:8791) __netdev_upper_dev_link (net/core/dev.c:8879 net/core/dev.c:8963) netdev_upper_dev_link (net/core/dev.c:9009) amt_newlink (drivers/net/amt.c:3321) | |
| Title | amt: Don't support cross-netns setup. | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:07:39.279Z
Reserved: 2026-09-11T19:38:34.794Z
Link: CVE-2026-90232
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:19.043
Modified: 2026-09-17T17:17:19.043
Link: CVE-2026-90232
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.