CVE-2023-52854

Updated: 2025-02-04 15:45:17.545814

Description:

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`.


Links NIST CIRCL RHEL Ubuntu

Severity

Severity Score
CVSS Version 2.x 0
CVSS Version 3.x HIGH 7.8

Status

OS name Project name Version Score Severity Status Errata Last updated

Statement

AlmaLinux 9.2 ESU kernel 5.14.0 7.8 HIGH Needs Triage 2025-02-04 11:16:31
AlmaLinux 9.2 FIPS kernel 5.14.0 7.8 HIGH Needs Triage 2025-02-04 11:16:30
Ubuntu 16.04 ELS linux-hwe 4.15.0 7.8 HIGH In Progress 2025-02-07 06:34:15
Ubuntu 18.04 ELS linux 4.15.0 7.8 HIGH In Progress 2025-02-07 22:53:38