CVE-2026-63989 (GCVE-0-2026-63989)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:56 – Updated: 2026-07-19 14:56
VLAI
Title
bridge: Fix sleep in atomic context in netlink path
Summary
In the Linux kernel, the following vulnerability has been resolved: bridge: Fix sleep in atomic context in netlink path Since the introduction of the netlink configuration path for bridge ports in commit 25c71c75ac87 ("bridge: bridge port parameters over netlink"), br_setport() was always called with the bridge lock held around it. Back then this decision made sense: The bridge lock protects the STP state of the bridge and its ports and at that time the function only processed three STP related netlink attributes (cost, priority and state). Nowadays, br_setport() processes a lot more attributes and most of them do not need the bridge lock: * Bridge flags: Only require RTNL. Read locklessly by the data path. Annotations can be added in net-next. * FDB port flushing: Only requires the FDB lock. * Multicast attributes: Only require the multicast lock. * Group forward mask: Only requires RTNL. Read locklessly by the data path. Annotations can be added in net-next. * Backup port and NHID: Only require RTNL. Read locklessly by the data path. This is a problem as the bridge calls dev_set_promiscuity() when certain bridge port flags change and this function can sleep since the commit cited below, resulting in a splat such as [1]. Fix this by reducing the scope of the bridge lock and only take it when processing the three STP related attributes that require it. This is consistent with the multicast attributes where each attribute acquires the multicast lock instead of having one critical section for all relevant attributes. [1] BUG: sleeping function called from invalid context at net/core/dev_addr_lists.c:1262 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 356, name: bridge preempt_count: 201, expected: 0 RCU nest depth: 0, expected: 0 2 locks held by bridge/356: #0: ffffffff919473a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg (net/core/rtnetlink.c:80 net/core/rtnetlink.c:7002) #1: ffff888115072d58 (&br->lock){+...}-{3:3}, at: br_setlink (./include/linux/spinlock.h:348 net/bridge/br_netlink.c:1117) Preemption disabled at: 0x0 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120) __might_resched.cold (kernel/sched/core.c:9163) netif_rx_mode_run (net/core/dev_addr_lists.c:1262) netif_rx_mode_sync (net/core/dev_addr_lists.c:1428) dev_set_promiscuity (net/core/dev_api.c:289) br_manage_promisc (net/bridge/br_if.c:135 net/bridge/br_if.c:172) br_port_flags_change (net/bridge/br_if.c:242 net/bridge/br_if.c:747) br_setport (net/bridge/br_netlink.c:1000) br_setlink (net/bridge/br_netlink.c:1118) rtnl_bridge_setlink (net/core/rtnetlink.c:5572) rtnetlink_rcv_msg (net/core/rtnetlink.c:7005) netlink_rcv_skb (net/netlink/af_netlink.c:2550) netlink_unicast (net/netlink/af_netlink.c:1318 net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sock_sendmsg (net/socket.c:787 (discriminator 4) net/socket.c:802 (discriminator 4)) ____sys_sendmsg (net/socket.c:2698) ___sys_sendmsg (net/socket.c:2752) __sys_sendmsg (net/socket.c:2784) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 78cd408356fe3edbac66598772fd347bf3e32c1f , < c9c2e609e8397bb57b4d73675f33a99183c4a0bd (git)
Affected: 78cd408356fe3edbac66598772fd347bf3e32c1f , < 803d39accfbdf223ccbb49684d5b5069b4c44586 (git)
Affected: 78cd408356fe3edbac66598772fd347bf3e32c1f , < 5eec4427b89c2fb2beac54920101e55a2f1c0c21 (git)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/bridge/br_netlink.c"
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
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              "versionType": "semver"
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              "versionType": "semver"
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      "cpeApplicability": [
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          "nodes": [
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                  "versionEndExcluding": "6.18.35",
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                  "vulnerable": true
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                  "versionEndExcluding": "7.1",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: Fix sleep in atomic context in netlink path\n\nSince the introduction of the netlink configuration path for bridge\nports in commit 25c71c75ac87 (\"bridge: bridge port parameters over\nnetlink\"), br_setport() was always called with the bridge lock held\naround it. Back then this decision made sense: The bridge lock protects\nthe STP state of the bridge and its ports and at that time the function\nonly processed three STP related netlink attributes (cost, priority and\nstate).\n\nNowadays, br_setport() processes a lot more attributes and most of them\ndo not need the bridge lock:\n\n* Bridge flags: Only require RTNL. Read locklessly by the data path.\n  Annotations can be added in net-next.\n\n* FDB port flushing: Only requires the FDB lock.\n\n* Multicast attributes: Only require the multicast lock.\n\n* Group forward mask: Only requires RTNL. Read locklessly by the data\n  path. Annotations can be added in net-next.\n\n* Backup port and NHID: Only require RTNL. Read locklessly by the data\n  path.\n\nThis is a problem as the bridge calls dev_set_promiscuity() when certain\nbridge port flags change and this function can sleep since the commit\ncited below, resulting in a splat such as [1].\n\nFix this by reducing the scope of the bridge lock and only take it when\nprocessing the three STP related attributes that require it. This is\nconsistent with the multicast attributes where each attribute acquires\nthe multicast lock instead of having one critical section for all\nrelevant attributes.\n\n[1]\nBUG: sleeping function called from invalid context at net/core/dev_addr_lists.c:1262\nin_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 356, name: bridge\npreempt_count: 201, expected: 0\nRCU nest depth: 0, expected: 0\n2 locks held by bridge/356:\n#0: ffffffff919473a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg (net/core/rtnetlink.c:80 net/core/rtnetlink.c:7002)\n#1: ffff888115072d58 (\u0026br-\u003elock){+...}-{3:3}, at: br_setlink (./include/linux/spinlock.h:348 net/bridge/br_netlink.c:1117)\nPreemption disabled at:\n 0x0\nHardware name: Bochs Bochs, BIOS Bochs 01/01/2011\nCall Trace:\n\u003cTASK\u003e\ndump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)\n__might_resched.cold (kernel/sched/core.c:9163)\nnetif_rx_mode_run (net/core/dev_addr_lists.c:1262)\nnetif_rx_mode_sync (net/core/dev_addr_lists.c:1428)\ndev_set_promiscuity (net/core/dev_api.c:289)\nbr_manage_promisc (net/bridge/br_if.c:135 net/bridge/br_if.c:172)\nbr_port_flags_change (net/bridge/br_if.c:242 net/bridge/br_if.c:747)\nbr_setport (net/bridge/br_netlink.c:1000)\nbr_setlink (net/bridge/br_netlink.c:1118)\nrtnl_bridge_setlink (net/core/rtnetlink.c:5572)\nrtnetlink_rcv_msg (net/core/rtnetlink.c:7005)\nnetlink_rcv_skb (net/netlink/af_netlink.c:2550)\nnetlink_unicast (net/netlink/af_netlink.c:1318 net/netlink/af_netlink.c:1344)\nnetlink_sendmsg (net/netlink/af_netlink.c:1894)\n__sock_sendmsg (net/socket.c:787 (discriminator 4) net/socket.c:802 (discriminator 4))\n____sys_sendmsg (net/socket.c:2698)\n___sys_sendmsg (net/socket.c:2752)\n__sys_sendmsg (net/socket.c:2784)\ndo_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\nentry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-19T14:56:10.396Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/c9c2e609e8397bb57b4d73675f33a99183c4a0bd"
        },
        {
          "url": "https://git.kernel.org/stable/c/803d39accfbdf223ccbb49684d5b5069b4c44586"
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        {
          "url": "https://git.kernel.org/stable/c/5eec4427b89c2fb2beac54920101e55a2f1c0c21"
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      ],
      "title": "bridge: Fix sleep in atomic context in netlink path",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63989",
    "datePublished": "2026-07-19T14:56:10.396Z",
    "dateReserved": "2026-07-19T07:54:57.025Z",
    "dateUpdated": "2026-07-19T14:56:10.396Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
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    "epss": {
      "cve": "CVE-2026-63989",
      "date": "2026-07-21",
      "epss": "0.00166",
      "percentile": "0.06195"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-63989\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T16:17:18.260\",\"lastModified\":\"2026-07-19T16:17:18.260\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbridge: Fix sleep in atomic context in netlink path\\n\\nSince the introduction of the netlink configuration path for bridge\\nports in commit 25c71c75ac87 (\\\"bridge: bridge port parameters over\\nnetlink\\\"), br_setport() was always called with the bridge lock held\\naround it. Back then this decision made sense: The bridge lock protects\\nthe STP state of the bridge and its ports and at that time the function\\nonly processed three STP related netlink attributes (cost, priority and\\nstate).\\n\\nNowadays, br_setport() processes a lot more attributes and most of them\\ndo not need the bridge lock:\\n\\n* Bridge flags: Only require RTNL. Read locklessly by the data path.\\n  Annotations can be added in net-next.\\n\\n* FDB port flushing: Only requires the FDB lock.\\n\\n* Multicast attributes: Only require the multicast lock.\\n\\n* Group forward mask: Only requires RTNL. Read locklessly by the data\\n  path. Annotations can be added in net-next.\\n\\n* Backup port and NHID: Only require RTNL. Read locklessly by the data\\n  path.\\n\\nThis is a problem as the bridge calls dev_set_promiscuity() when certain\\nbridge port flags change and this function can sleep since the commit\\ncited below, resulting in a splat such as [1].\\n\\nFix this by reducing the scope of the bridge lock and only take it when\\nprocessing the three STP related attributes that require it. This is\\nconsistent with the multicast attributes where each attribute acquires\\nthe multicast lock instead of having one critical section for all\\nrelevant attributes.\\n\\n[1]\\nBUG: sleeping function called from invalid context at net/core/dev_addr_lists.c:1262\\nin_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 356, name: bridge\\npreempt_count: 201, expected: 0\\nRCU nest depth: 0, expected: 0\\n2 locks held by bridge/356:\\n#0: ffffffff919473a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg (net/core/rtnetlink.c:80 net/core/rtnetlink.c:7002)\\n#1: ffff888115072d58 (\u0026br-\u003elock){+...}-{3:3}, at: br_setlink (./include/linux/spinlock.h:348 net/bridge/br_netlink.c:1117)\\nPreemption disabled at:\\n 0x0\\nHardware name: Bochs Bochs, BIOS Bochs 01/01/2011\\nCall Trace:\\n\u003cTASK\u003e\\ndump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)\\n__might_resched.cold (kernel/sched/core.c:9163)\\nnetif_rx_mode_run (net/core/dev_addr_lists.c:1262)\\nnetif_rx_mode_sync (net/core/dev_addr_lists.c:1428)\\ndev_set_promiscuity (net/core/dev_api.c:289)\\nbr_manage_promisc (net/bridge/br_if.c:135 net/bridge/br_if.c:172)\\nbr_port_flags_change (net/bridge/br_if.c:242 net/bridge/br_if.c:747)\\nbr_setport (net/bridge/br_netlink.c:1000)\\nbr_setlink (net/bridge/br_netlink.c:1118)\\nrtnl_bridge_setlink (net/core/rtnetlink.c:5572)\\nrtnetlink_rcv_msg (net/core/rtnetlink.c:7005)\\nnetlink_rcv_skb (net/netlink/af_netlink.c:2550)\\nnetlink_unicast (net/netlink/af_netlink.c:1318 net/netlink/af_netlink.c:1344)\\nnetlink_sendmsg (net/netlink/af_netlink.c:1894)\\n__sock_sendmsg (net/socket.c:787 (discriminator 4) net/socket.c:802 (discriminator 4))\\n____sys_sendmsg (net/socket.c:2698)\\n___sys_sendmsg (net/socket.c:2752)\\n__sys_sendmsg (net/socket.c:2784)\\ndo_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\\nentry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/bridge/br_netlink.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"78cd408356fe3edbac66598772fd347bf3e32c1f\",\"lessThan\":\"c9c2e609e8397bb57b4d73675f33a99183c4a0bd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"78cd408356fe3edbac66598772fd347bf3e32c1f\",\"lessThan\":\"803d39accfbdf223ccbb49684d5b5069b4c44586\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"78cd408356fe3edbac66598772fd347bf3e32c1f\",\"lessThan\":\"5eec4427b89c2fb2beac54920101e55a2f1c0c21\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/bridge/br_netlink.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.12\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/5eec4427b89c2fb2beac54920101e55a2f1c0c21\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/803d39accfbdf223ccbb49684d5b5069b4c44586\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c9c2e609e8397bb57b4d73675f33a99183c4a0bd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-07-21T15:55:06+00:00",
      "cve": "CVE-2026-63989",
      "id": "CVE-2026-63989",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bridge: Fix sleep in atomic context in netlink path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63989.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-21T13:02:04Z",
      "cve": "CVE-2026-63989",
      "id": "CVE-2026-63989",
      "initial_release_date": "2026-07-21T13:02:04Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-63989",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63989.json",
      "version": "2"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.