{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-23419",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-23419"
  ],
  "published": "2026-04-03T13:28:18Z",
  "summary": "net/rds: Fix circular locking dependency in rds_tcp_tune",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/rds: Fix circular locking dependency in rds_tcp_tune\n\nsyzbot reported a circular locking dependency in rds_tcp_tune() where\nsk_net_refcnt_upgrade() is called while holding the socket lock:\n\n======================================================\nWARNING: possible circular locking dependency detected\n======================================================\nkworker/u10:8/15040 is trying to acquire lock:\nffffffff8e9aaf80 (fs_reclaim){+.+.}-{0:0},\nat: __kmalloc_cache_noprof+0x4b/0x6f0\n\nbut task is already holding lock:\nffff88805a3c1ce0 (k-sk_lock-AF_INET6){+.+.}-{0:0},\nat: rds_tcp_tune+0xd7/0x930\n\nThe issue occurs because sk_net_refcnt_upgrade() performs memory\nallocation (via get_net_track() -> ref_tracker_alloc()) while the\nsocket lock is held, creating a circular dependency with fs_reclaim.\n\nFix this by moving sk_net_refcnt_upgrade() outside the socket lock\ncritical section. This is safe because the fields modified by the\nsk_net_refcnt_upgrade() call (sk_net_refcnt, ns_tracker) are not\naccessed by any concurrent code path at this point.\n\nv2:\n  - Corrected fixes tag\n  - check patch line wrap nits\n  - ai commentary nits",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null,
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-23419"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8babb271403378ba6836f6c8599c5313d0e2355d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8519e6883a942e510f33a0e634e27bcc3a844a40"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6ce948fa54599f369ff7fe8b793a6aae4b0762b2"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/026bbaeeab9e04534ee58882b6447300629b42f6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6a877ececd6daa002a9a0002cd0fbca6592a9244"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.5,
      "cvss_v3_severity": "High",
      "scenario": "AV:N - RDS/TCP creates a listener on TCP port 16385, and an unauthenticated remote TCP connection reaches rds_tcp_accept_one() and rds_tcp_tune() before protocol-level validation. A local AF_RDS path also exists, but the highest reasonable vector is network.\nAC:L - The attacker can repeatedly trigger the vulnerable lock ordering by opening RDS/TCP connections; no special packet format, credentials, or attacker-uncontrolled race is needed to reach the bad allocation-under-socket-lock path. Applying the higher-severity rule, this is Low complexity.\nPR:N - The network accept path requires no local account, capabilities, or RDS authentication before rds_tcp_tune() is invoked. Remote reachability to the RDS/TCP listener is sufficient in a reasonable affected deployment.\nUI:N - No victim user action is required. The attacker can initiate the connection directly.\nS:U - The issue affects kernel locking within the same host security authority. It does not cross a VM, container, IOMMU, or other separate security scope boundary.\nC:N - The bug is a circular locking dependency involving sk_lock, sk_net_refcnt_upgrade(), ref_tracker allocation, and fs_reclaim. It does not expose kernel memory or create a read primitive.\nI:N - There is no memory corruption or write primitive; the fix only moves a refcount-tracker allocation outside the socket lock. Integrity is not directly impacted.\nA:H - The lock inversion can lead to a kernel deadlock or system hang, and syzbot reported it as a possible deadlock in the RDS accept worker. Kernel deadlock is High availability impact."
    }
  }
}