{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-52854",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2023-52854"
  ],
  "published": "2024-05-21T15:34:20Z",
  "summary": "padata: Fix refcnt handling in padata_free_shell()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npadata: Fix refcnt handling in padata_free_shell()\n\nIn a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead\nto system UAF (Use-After-Free) issues. Due to the lengthy analysis of\nthe pcrypt_aead01 function call, I'll describe the problem scenario\nusing a simplified model:\n\nSuppose there's a user of padata named `user_function` that adheres to\nthe padata requirement of calling `padata_free_shell` after `serial()`\nhas been invoked, as demonstrated in the following code:\n\n```c\nstruct request {\n    struct padata_priv padata;\n    struct completion *done;\n};\n\nvoid parallel(struct padata_priv *padata) {\n    do_something();\n}\n\nvoid serial(struct padata_priv *padata) {\n    struct request *request = container_of(padata,\n    \t\t\t\tstruct request,\n\t\t\t\tpadata);\n    complete(request->done);\n}\n\nvoid user_function() {\n    DECLARE_COMPLETION(done)\n    padata->parallel = parallel;\n    padata->serial = serial;\n    padata_do_parallel();\n    wait_for_completion(&done);\n    padata_free_shell();\n}\n```\n\nIn the corresponding padata.c file, there's the following code:\n\n```c\nstatic void padata_serial_worker(struct work_struct *serial_work) {\n    ...\n    cnt = 0;\n\n    while (!list_empty(&local_list)) {\n        ...\n        padata->serial(padata);\n        cnt++;\n    }\n\n    local_bh_enable();\n\n    if (refcount_sub_and_test(cnt, &pd->refcnt))\n        padata_free_pd(pd);\n}\n```\n\nBecause of the high system load and the accumulation of unexecuted\nsoftirq at this moment, `local_bh_enable()` in padata takes longer\nto execute than usual. Subsequently, when accessing `pd->refcnt`,\n`pd` has already been released by `padata_free_shell()`, resulting\nin a UAF issue with `pd->refcnt`.\n\nThe fix is straightforward: add `refcount_dec_and_test` before calling\n`padata_free_pd` in `padata_free_shell`.",
  "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": "6.1.63",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-52854"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/41aad9d6953984d134fc50f631f24ef476875d4d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0dd34a7ad395dbcf6ae60e48e9786050e25b9bc5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c7c26d0ef5d20f00dbb2ae3befcabbe0efa77275"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1e901bcb8af19416b65f5063a4af7996e5a51d7f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1734a79e951914f1db2c65e635012a35db1c674b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7ddc21e317b360c3444de3023bcc83b85fabae2f"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-05-24T06:48:58Z"
  }
}