CVE-2023-52854

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`.

Gravité et risque d'exploitation

CVE-2023-52854 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.24 %, ce qui la place devant 14.5 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <1e901bcb8af19416b65f5063a4af7996e5a51d7f, <=6.1.*, 13721e447acc2b82c19cf72e9e6c4291c77693ed, 3.16.84, 6.6.2, 5fefc9b3e3584a1ce98da27c38e1b8dda1939d74, 0, <1734a79e951914f1db2c65e635012a35db1c674b, 07928d9bfc81640bab36f5190e8725894d93b659, 6.5.12, 6.1.63, <41aad9d6953984d134fc50f631f24ef476875d4d, <4.10, <7ddc21e317b360c3444de3023bcc83b85fabae2f, 5.10.201, <4.20, 5.6, <=5.10.*, <=6.6.*, c9da8ee1491719001a444f4af688b75e72b58418, 928cf3d733c4efc221e1a78b14cb2ee066627260, 4.9.215, <4.5, 4.14.172, 5.15.139, 4.4.215, dc34710a7aba5207e7cb99d11588c04535b3c53d, 5.4.19, <5.5, 5.5.3, <c7c26d0ef5d20f00dbb2ae3befcabbe0efa77275, <0dd34a7ad395dbcf6ae60e48e9786050e25b9bc5, <5.6, 4.19.103, 7a2ccb65f90168edc2348495bb56093c466ffa39, <=*, <=5.15.*, <=6.5.*, <3.17, 6.7, <4.15, 26daf8e6515c2dcd25d235468420b9f46e0acdac) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/41aad9d6953984d134fc50f631f24ef476875d4d
• https://git.kernel.org/stable/c/0dd34a7ad395dbcf6ae60e48e9786050e25b9bc5
• https://git.kernel.org/stable/c/c7c26d0ef5d20f00dbb2ae3befcabbe0efa77275
• https://git.kernel.org/stable/c/1e901bcb8af19416b65f5063a4af7996e5a51d7f
• https://git.kernel.org/stable/c/1734a79e951914f1db2c65e635012a35db1c674b
• https://git.kernel.org/stable/c/7ddc21e317b360c3444de3023bcc83b85fabae2f