CVE-2026-90071 (GCVE-0-2026-90071)
Vulnerability from cvelistv5
Published
2026-09-17 16:05
Modified
2026-10-19 08:57
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: restore skb->dev on the slave failure path teql_master_xmit() sets skb->dev = slave before calling the slave's ndo_start_xmit(), but never restores it when that transmit fails. The skb then walks on to the next slave still pointing at the previous one. If a later slave has no resolved neighbour, teql_resolve() hands the skb to neigh_event_send(), which queues it on that neighbour's arp_queue with the stale skb->dev. skb->dev holds no reference, so deleting the previous slave frees the net_device while the skb is still queued. Whatever runs next on that skb - arp_error_report() on timeout, or neigh_direct_output() -> dev_queue_xmit() once the neighbour resolves - causes a UAF like the one below: BUG: KASAN: slab-use-after-free in __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) Read of size 4 at addr ffff888106e100b0 by task flood_packet/527 CPU: 0 UID: 0 PID: 527 Comm: flood_packet Not tainted 7.2.0-rc6-g594d90519502 #1 PREEMPT(lazy) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <IRQ> dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120) print_report (mm/kasan/report.c:378 mm/kasan/report.c:482) ? __pfx__raw_spin_lock_irqsave (./include/asm-generic/qrwlock.h:122 (discriminator 4)) ? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) kasan_report (mm/kasan/report.c:595) ? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) [...] ipv4_link_failure (net/ipv4/route.c:1251 net/ipv4/route.c:1258) ? __pfx_ipv4_link_failure (./include/linux/skbuff.h:4327) ? _raw_write_lock (./include/linux/instrumented.h:55 ./include/linux/atomic/atomic-instrumented.h:1301 ./include/asm-generic/qrwlock.h:98 ./include/linux/rwlock_api_smp.h:230 kernel/locking/spinlock.c:304) ? __pfx__raw_write_lock (kernel/locking/spinlock.c:175) arp_error_report (./include/net/dst.h:438 net/ipv4/arp.c:296) neigh_invalidate (net/core/neighbour.c:1077) neigh_timer_handler (net/core/neighbour.c:1169) [...] Allocated by task 505: kasan_save_stack (mm/kasan/common.c:57) kasan_save_track (mm/kasan/common.c:78) __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415) __kvmalloc_node_noprof (./include/linux/kasan.h:263 mm/slub.c:5334 mm/slub.c:6905) alloc_netdev_mqs (net/core/dev.c:12055 (discriminator 2)) rtnl_create_link (net/core/rtnetlink.c:3721) rtnl_newlink (net/core/rtnetlink.c:3903 net/core/rtnetlink.c:4044 net/core/rtnetlink.c:4159) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) [...] Freed by task 536: kasan_save_stack (mm/kasan/common.c:57) kasan_save_track (mm/kasan/common.c:78) kasan_save_free_info (mm/kasan/generic.c:584) __kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285) kfree (./include/linux/kasan.h:235 mm/slub.c:2677 mm/slub.c:6377 mm/slub.c:6692) device_release (drivers/base/core.c:2636) kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737) netdev_run_todo (net/core/dev.c:11756) rtnl_dellink (net/core/rtnetlink.c:157 ./include/linux/rtnetlink.h:135 net/core/rtnetlink.c:3651) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) [...] Fix this by restoring skb->dev to the master at the end of each slave's iteration.
References
Impacted products
Vendor Product Version
Linux Linux Version: 383493b9940e3d1b5517424081b3e072e20ec43c
Version: 6b1f563d670162e188a0f2aec39c24b67b106e17
Version: 57c153249143333bbf4ecf927bdf8aa2696ee397
Version: 59b06d8b9bdb6b64b3c534c18da68bce5ccd31be
Version: 81a43e8005366f16e629d8c95dfe05beaa8d36a7
Version: 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4
Version: 0cc0c2e661af418bbf7074179ea5cfffc0a5c466
Version: 0cc0c2e661af418bbf7074179ea5cfffc0a5c466
Version: 21ea283c2750c8307aa35ee832b0951cc993c27d
Version: 5.10.253   ≤
Version: 5.15.203   ≤
Version: 6.1.167   ≤
Version: 6.6.130   ≤
Version: 6.12.78   ≤
Version: 6.18.19   ≤
Version: 6.19.9   ≤
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_teql: restore skb-\u003edev on the slave failure path\n\nteql_master_xmit() sets skb-\u003edev = slave before calling the slave\u0027s\nndo_start_xmit(), but never restores it when that transmit fails. The\nskb then walks on to the next slave still pointing at the previous one.\n\nIf a later slave has no resolved neighbour, teql_resolve() hands the skb\nto neigh_event_send(), which queues it on that neighbour\u0027s arp_queue\nwith the stale skb-\u003edev. skb-\u003edev holds no reference, so deleting the\nprevious slave frees the net_device while the skb is still queued.\nWhatever runs next on that skb - arp_error_report() on timeout, or\nneigh_direct_output() -\u003e dev_queue_xmit() once the neighbour resolves -\ncauses a UAF like the one below:\n\nBUG: KASAN: slab-use-after-free in __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))\nRead of size 4 at addr ffff888106e100b0 by task flood_packet/527\nCPU: 0 UID: 0 PID: 527 Comm: flood_packet Not tainted 7.2.0-rc6-g594d90519502 #1 PREEMPT(lazy)\nHardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nCall Trace:\n\u003cIRQ\u003e\ndump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)\nprint_report (mm/kasan/report.c:378 mm/kasan/report.c:482)\n? __pfx__raw_spin_lock_irqsave (./include/asm-generic/qrwlock.h:122 (discriminator 4))\n? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))\nkasan_report (mm/kasan/report.c:595)\n? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2))\n__icmp_send (net/ipv4/icmp.c:914 (discriminator 2))\n[...]\nipv4_link_failure (net/ipv4/route.c:1251 net/ipv4/route.c:1258)\n? __pfx_ipv4_link_failure (./include/linux/skbuff.h:4327)\n? _raw_write_lock (./include/linux/instrumented.h:55 ./include/linux/atomic/atomic-instrumented.h:1301 ./include/asm-generic/qrwlock.h:98 ./include/linux/rwlock_api_smp.h:230 kernel/locking/spinlock.c:304)\n? __pfx__raw_write_lock (kernel/locking/spinlock.c:175)\narp_error_report (./include/net/dst.h:438 net/ipv4/arp.c:296)\nneigh_invalidate (net/core/neighbour.c:1077)\nneigh_timer_handler (net/core/neighbour.c:1169)\n[...]\nAllocated by task 505:\nkasan_save_stack (mm/kasan/common.c:57)\nkasan_save_track (mm/kasan/common.c:78)\n__kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)\n__kvmalloc_node_noprof (./include/linux/kasan.h:263 mm/slub.c:5334 mm/slub.c:6905)\nalloc_netdev_mqs (net/core/dev.c:12055 (discriminator 2))\nrtnl_create_link (net/core/rtnetlink.c:3721)\nrtnl_newlink (net/core/rtnetlink.c:3903 net/core/rtnetlink.c:4044 net/core/rtnetlink.c:4159)\nrtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n[...]\nFreed by task 536:\nkasan_save_stack (mm/kasan/common.c:57)\nkasan_save_track (mm/kasan/common.c:78)\nkasan_save_free_info (mm/kasan/generic.c:584)\n__kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285)\nkfree (./include/linux/kasan.h:235 mm/slub.c:2677 mm/slub.c:6377 mm/slub.c:6692)\ndevice_release (drivers/base/core.c:2636)\nkobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)\nnetdev_run_todo (net/core/dev.c:11756)\nrtnl_dellink (net/core/rtnetlink.c:157 ./include/linux/rtnetlink.h:135 net/core/rtnetlink.c:3651)\nrtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n[...]\n\nFix this by restoring skb-\u003edev to the master at the end of each slave\u0027s\niteration."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - teql_master_xmit() itself writes skb-\u003edev to the slave, and the UAF is completed by a local RTM_DELLINK (rtnl_dellink \u2192 netdev_run_todo) of that slave while the skb sits on another slave\u0027s arp_queue; the packet reaches teql_master_xmit via sendto/udp_sendmsg \u2192 ip_finish_output2 \u2192 __dev_queue_xmit on teql0, not via a remote protocol field.\nAC:L - The attacker chooses the slaves, sends on teql0 so teql_master_xmit() leaves skb-\u003edev on a failed ndo_start_xmit/netif_xmit_frozen_or_stopped slave, then teql_resolve()/neigh_event_send() queues that skb for an unresolved neighbour, then issues RTM_DELLINK; flood_packet plus an unanswered ARP destination make this repeatable without third-party timing.\nPR:L - RTM_NEWLINK, RTM_NEWQDISC (tc_modify_qdisc \u2192 teql_qdisc_init) and the freeing RTM_DELLINK all go through rtnetlink_rcv_msg(), which requires netlink_net_capable(skb, CAP_NET_ADMIN) against sock_net(skb-\u003esk)-\u003euser_ns; unshare -Urn grants that namespaced capability without init-namespace root.\nUI:N - The attacker alone creates the slaves, grafts the teql0 qdisc, injects packets into teql_master_xmit(), and deletes the stale skb-\u003edev slave with RTM_DELLINK; no other user must open a file, mount a volume, or otherwise act.\nS:U - The freed object is a kernel net_device from alloc_netdev_mqs()/rtnl_newlink, used later on the same host via skb-\u003edev in __icmp_send() or dev_queue_xmit(); this is in-kernel memory corruption, not a VM, IOMMU, or hypervisor boundary crossing.\nC:H - KASAN reports a slab-use-after-free read of the freed net_device in __icmp_send() (skb_in-\u003edev-\u003eflags) from arp_error_report(); the same dangling skb-\u003edev is consumed by neigh_direct_output() \u2192 dev_queue_xmit(), and reclaim of that slab object yields an arbitrary kernel read.\nI:H - Once the neighbour resolves, neigh_update_process_arp_queue() calls neigh_direct_output() \u2192 dev_queue_xmit() on the dangling skb-\u003edev, so a reclaimed net_device\u0027s netdev_ops (ndo_start_xmit) become attacker-controlled, giving an arbitrary kernel write and control-flow hijack.\nA:H - The reported path is neigh_timer_handler() \u2192 neigh_invalidate() \u2192 arp_error_report() \u2192 ipv4_link_failure() \u2192 __icmp_send() hitting a KASAN slab-use-after-free of the deleted slave net_device, which oopses/panics the kernel even without further exploitation."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:28.331Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1360bc93f5be1be3cf937ebea667b3418dd30a79"
        },
        {
          "url": "https://git.kernel.org/stable/c/d453bf439ef230b5743afc25e194adacca8c6e43"
        },
        {
          "url": "https://git.kernel.org/stable/c/012559cf3c67ce8825a31d4f66b040b6fbaf775e"
        },
        {
          "url": "https://git.kernel.org/stable/c/aa39a790d56b40bfcf3861653ceb46a3a113adb6"
        },
        {
          "url": "https://git.kernel.org/stable/c/00d8a387b23b7831ad9919256a6b9caaa10f19c3"
        },
        {
          "url": "https://git.kernel.org/stable/c/96bc345a3f17543d0d92ada609e02198d6380e26"
        },
        {
          "url": "https://git.kernel.org/stable/c/0cd75037948567193f7f5767176538822ce23873"
        },
        {
          "url": "https://git.kernel.org/stable/c/dc4b95b8fee95113587e93ca116356032d271371"
        }
      ],
      "title": "net/sched: sch_teql: restore skb-\u003edev on the slave failure path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90071",
    "datePublished": "2026-09-17T16:05:52.245Z",
    "dateReserved": "2026-09-11T19:38:34.784Z",
    "dateUpdated": "2026-10-19T08:57:28.331Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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