{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-35954",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-35954"
  ],
  "published": "2024-05-20T09:42:41Z",
  "summary": "scsi: sg: Avoid sg device teardown race",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: sg: Avoid sg device teardown race\n\nsg_remove_sfp_usercontext() must not use sg_device_destroy() after calling\nscsi_device_put().\n\nsg_device_destroy() is accessing the parent scsi_device request_queue which\nwill already be set to NULL when the preceding call to scsi_device_put()\nremoved the last reference to the parent scsi_device.\n\nThe resulting NULL pointer exception will then crash the kernel.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.6.20-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-2712",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v6",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7l",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v8",
            "binary_version": "1:6.6.20-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.6.20-1+rpt1": {
            "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668",
            "upstream_version": "6.6.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.28"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-35954"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/46af9047523e2517712ae8e71d984286c626e022"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b0d1ebcc1a9560e494ea9b3ee808540db26c5086"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/27f58c04a8f438078583041468ec60597841284d"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable path is entered by opening and closing the `/dev/sgN` character device, i.e. local file/syscall access to the SCSI generic driver. There is no network-facing consumer of `sg_remove_sfp_usercontext()`.\nAC:L - The attacker holds one side of the race directly (it owns the open sg fd and chooses when to `close()`), and can supply the other side by hot-unplugging its own removable SCSI/USB storage or by looping open/close across a hot-unplug; once sg holds the last `scsi_device` reference the ordering bug fires deterministically, and the attempt is freely repeatable.\nPR:L - No capability check exists on this path \u2014 only DAC permission on `/dev/sgN`, which is granted to the unprivileged `disk` group on mainstream distros and is world-accessible on many embedded/appliance and storage-software deployments; the device-removal side (physical unplug, transport loss, hypervisor hot-unplug) needs no privilege either.\nUI:N - The attacker performs the `open()`, triggers the device teardown, and performs the final `close()` from its own process; no victim action is required.\nS:U - The use-after-free and the resulting corruption are confined to kernel memory within the same security authority, with no VM, IOMMU, or sandbox boundary crossed.\nC:H - `sg_device_destroy()` dereferences the already-`kfree()`d `struct scsi_device`, and the reclaimed slab can be groomed so the stale `request_queue` pointer aims `blk_trace_remove()`/`blk_put_queue()` at attacker-chosen kernel memory, yielding a leverageable kernel-memory disclosure primitive.\nI:H - The stale pointer loaded from freed memory is used for writes \u2014 `mutex_lock(&q->debugfs_mutex)`, `rcu_replace_pointer(q->blk_trace, NULL)`, and `refcount_dec_and_test(&q->refs)` \u2014 so a reallocated slab gives a controlled write into kernel memory and a path to control-flow hijack.\nA:H - In the common case the stale value is NULL and `blk_trace_remove(NULL)`/`blk_put_queue(NULL)` immediately oops the kernel, as stated in the fix commit; the crash is repeatable and takes down the whole system."
    }
  }
}