ghsa-gj4h-wmhg-vp66
Vulnerability from github
Published
2024-05-21 18:31
Modified
2025-02-03 18:30
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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:

```c 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:

```c 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.

Show details on source website

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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'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`.",
   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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