GHSA-GJ4H-WMHG-VP66

Vulnerability from github – Published: 2024-05-21 18:31 – Updated: 2025-02-03 18:30
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

padata: Fix refcnt handling in padata_free_shell()

In a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead to system UAF (Use-After-Free) issues. Due to the lengthy analysis of the pcrypt_aead01 function call, I'll describe the problem scenario using a simplified model:

Suppose there's a user of padata named user_function that adheres to the padata requirement of calling padata_free_shell after serial() has been invoked, as demonstrated in the following code:

struct request {
    struct padata_priv padata;
    struct completion *done;
};

void parallel(struct padata_priv *padata) {
    do_something();
}

void serial(struct padata_priv *padata) {
    struct request *request = container_of(padata,
                    struct request,
                padata);
    complete(request->done);
}

void user_function() {
    DECLARE_COMPLETION(done)
    padata->parallel = parallel;
    padata->serial = serial;
    padata_do_parallel();
    wait_for_completion(&done);
    padata_free_shell();
}

In the corresponding padata.c file, there's the following code:

static void padata_serial_worker(struct work_struct *serial_work) {
    ...
    cnt = 0;

    while (!list_empty(&local_list)) {
        ...
        padata->serial(padata);
        cnt++;
    }

    local_bh_enable();

    if (refcount_sub_and_test(cnt, &pd->refcnt))
        padata_free_pd(pd);
}

Because of the high system load and the accumulation of unexecuted softirq at this moment, local_bh_enable() in padata takes longer to execute than usual. Subsequently, when accessing pd->refcnt, pd has already been released by padata_free_shell(), resulting in a UAF issue with pd->refcnt.

The fix is straightforward: add refcount_dec_and_test before calling padata_free_pd in padata_free_shell.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2023-52854"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-21T16:15:22Z",
    "severity": "HIGH"
  },
  "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\u0027ll describe the problem scenario\nusing a simplified model:\n\nSuppose there\u0027s 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-\u003edone);\n}\n\nvoid user_function() {\n    DECLARE_COMPLETION(done)\n    padata-\u003eparallel = parallel;\n    padata-\u003eserial = serial;\n    padata_do_parallel();\n    wait_for_completion(\u0026done);\n    padata_free_shell();\n}\n```\n\nIn the corresponding padata.c file, there\u0027s 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(\u0026local_list)) {\n        ...\n        padata-\u003eserial(padata);\n        cnt++;\n    }\n\n    local_bh_enable();\n\n    if (refcount_sub_and_test(cnt, \u0026pd-\u003erefcnt))\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-\u003erefcnt`,\n`pd` has already been released by `padata_free_shell()`, resulting\nin a UAF issue with `pd-\u003erefcnt`.\n\nThe fix is straightforward: add `refcount_dec_and_test` before calling\n`padata_free_pd` in `padata_free_shell`.",
  "id": "GHSA-gj4h-wmhg-vp66",
  "modified": "2025-02-03T18:30:37Z",
  "published": "2024-05-21T18:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-52854"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0dd34a7ad395dbcf6ae60e48e9786050e25b9bc5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1734a79e951914f1db2c65e635012a35db1c674b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1e901bcb8af19416b65f5063a4af7996e5a51d7f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/41aad9d6953984d134fc50f631f24ef476875d4d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ddc21e317b360c3444de3023bcc83b85fabae2f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c7c26d0ef5d20f00dbb2ae3befcabbe0efa77275"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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