GHSA-7H9J-J2H3-3XHW
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In 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.
-
amt_lookup_upper_dev() looks up an upper device in the lower device's netns only
-
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: 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) _syssendmsg (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)
{
"affected": [],
"aliases": [
"CVE-2026-90232"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:19Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\namt: Don\u0027t support cross-netns setup.\n\nWhen a lower device is unregistered, amt_device_event() tries\nto unregister its upper AMT device, but it has two problems.\n\n 1. amt_lookup_upper_dev() looks up an upper device in the\n lower device\u0027s netns only\n\n 2. amt_device_event() unregisters a single upper device only\n\nIf AMT device is created on a lower device in another netns,\nremoving the lower device triggers the splat below and gets\nstuck until all upper devices are removed. [0]\n\nThe cross-netns setup seems unintentional considering 1. and\nthe following points:\n\n * amt_link_setup() sets dev-\u003enetns_immutable to true\n * skb_scrub_packet() is not called in the fast path\n * iproute2 binary fails to find cross-netns lower device via\n link-netns:\n # ip -n ns1 link add amt0 link-netns ns2 type amt dev veth1\n Cannot find device \"veth1\"\n\nInstead of supporting it properly and preparing for per-netns\nnetdev unreg, let\u0027s forbid cross-netns setup.\n\nNote that the problem 2. needs a separate fix.\n\n[0]:\nWARNING: net/core/dev.c:12518 at unregister_netdevice_many_notify+0x1cce/0x2250, CPU#48: ip/2031\nModules linked in:\nCPU: 48 UID: 0 PID: 2031 Comm: ip Not tainted 7.2.0-rc5+ #27 PREEMPT(full)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\nRIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:12518)\nCode: 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 \u003c0f\u003e 0b 90 eb 81 48 8d 3d f6 3b 9c 02 48 c7 c6 c0 0b 63 84 ba e2 1f\nRSP: 0018:ffffc90004abf160 EFLAGS: 00010212\nRAX: ffff888104d38260 RBX: ffff88800b0911b8 RCX: dffffc0000000000\nRDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff85b9f880\nRBP: ffffc90004abf2d0 R08: ffffffff85b9f887 R09: 1ffffffff0b73f10\nR10: dffffc0000000000 R11: fffffbfff0b73f11 R12: ffff88800b091d08\nR13: ffff88800b091178 R14: dffffc0000000000 R15: ffff88800b091000\nFS: 00007f555b86c600(0000) GS:ffff8881942a0000(0000) knlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562107d489c0 CR3: 0000000109a40002 CR4: 0000000000372ef0\nCall Trace:\n \u003cTASK\u003e\n rtnl_dellink (net/core/rtnetlink.c:3632 net/core/rtnetlink.c:3674)\n rtnetlink_rcv_msg (net/core/rtnetlink.c:7112)\n netlink_rcv_skb (net/netlink/af_netlink.c:2556)\n netlink_unicast (net/netlink/af_netlink.c:1319)\n netlink_sendmsg (net/netlink/af_netlink.c:1900)\n ____sys_sendmsg (net/socket.c:775)\n __sys_sendmsg (net/socket.c:2738)\n do_syscall_64 (arch/x86/entry/syscall_64.c:63)\n entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n...\nunregister_netdevice: waiting for veth0 to become free. Usage count = 7\nref_tracker: netdev@ffff88800d7496d8 has 3/3 users at\n __netdev_adjacent_dev_insert (./include/linux/netdevice.h:4525 ./include/linux/netdevice.h:4554 net/core/dev.c:8791)\n __netdev_upper_dev_link (net/core/dev.c:8879 net/core/dev.c:8963)\n netdev_upper_dev_link (net/core/dev.c:9009)\n amt_newlink (drivers/net/amt.c:3321)",
"id": "GHSA-7h9j-j2h3-3xhw",
"modified": "2026-09-17T18:31:57Z",
"published": "2026-09-17T18:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90232"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/569eb11f0990849ba48706a2bfa743273707e254"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e1dc0af719a2566ae7ccb82c0a11f70aa54908e9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e99ecc3046ea5f5c6b5e1f8b4ef854c6c6998e06"
}
],
"schema_version": "1.4.0",
"severity": []
}
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