{"cve":"CVE-2023-52854","nvd":{"published":"2024-05-21T16:15:22.377","modified":"2026-06-17T06:43:44.443","status":"Analyzed","description":"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`.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/0dd34a7ad395dbcf6ae60e48e9786050e25b9bc5","https://git.kernel.org/stable/c/1734a79e951914f1db2c65e635012a35db1c674b","https://git.kernel.org/stable/c/1e901bcb8af19416b65f5063a4af7996e5a51d7f","https://git.kernel.org/stable/c/41aad9d6953984d134fc50f631f24ef476875d4d","https://git.kernel.org/stable/c/7ddc21e317b360c3444de3023bcc83b85fabae2f"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2023-52854","score":0.00242,"percentile":0.15471,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}