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net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister() syzbot reported a memory leak [1] in the UDP tunnel NIC offload code. When device registration fails (e.g. in register_netdevice()), netdev core unwinds by sending a single NETDEV_UNREGISTER notification. If work was queued during NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister() returns early: if (utn->work_pending) return; Because failed registrations do not enter netdev_wait_allrefs_any(), no subsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the struct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked permanently. Fix this by removing the early return. Instead, synchronously cancel any pending work with cancel_delayed_work_sync() before freeing @utn. To be able to call cancel_delayed_work_sync() while holding RTNL (the work also needs RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL is contended, requeue the work with a 1 jiffy delay (via queue_delayed_work()) to prevent high CPU contention while waiting for RTNL lock. The utn->work_pending bookkeeping is no longer needed and is removed, as the workqueue core already tracks the pending/running state of the work. [1] BUG: memory leak unreferenced object 0xffff888127d5f840 (size 96): comm "syz-executor", pid 5806, jiffies 4294942188 backtrace (crc 99fdb6c8): __kmalloc_noprof+0x3bf/0x550 udp_tunnel_nic_alloc net/ipv4/

Announced Source revision 1
Original source ↗

CVE-2026-74543

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74543

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
        "lessThan": "52c753b46265243406690d980faa9514d3f53827",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
        "lessThan": "b712da45bd9b9835d132e9fbc0c3e43c164cb1fd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
        "lessThan": "f82a2ded3d7a9098267c84f14eafdb98c4550ac5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
        "lessThan": "b322532a4b774db1b480a2de84125910a70739a5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
        "lessThan": "080695e6f005e2396f1207fd69d24c442cb230c6",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv4/udp_tunnel_nic.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.9"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.9",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.103",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.44",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.8",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv4/udp_tunnel_nic.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74543

Source reference: /cveMetadata/cveId

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Event
#46573 · Revision 1
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