CVSS 7.8 · High EPSS 0,24%
Kerentanan Use After Free pada linux kernel. Skor CVSS 3.1 7.8 (High) menurut NVD.
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`.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
· uraikan di kalkulator | Vendor | Produk | Versi terdampak |
|---|---|---|
| linux | linux kernel | Versi 3.16.84 hingga sebelum 3.17 |
| linux | linux kernel | Versi 4.4.215 hingga sebelum 4.5 |
| linux | linux kernel | Versi 4.9.215 hingga sebelum 4.10 |
| linux | linux kernel | Versi 4.14.172 hingga sebelum 4.15 |
| linux | linux kernel | Versi 4.19.103 hingga sebelum 4.20 |
| linux | linux kernel | Versi 5.4.19 hingga sebelum 5.5 |
| linux | linux kernel | Versi 5.5.3 hingga sebelum 5.10.201 |
| linux | linux kernel | Versi 5.11 hingga sebelum 5.15.139 |
| linux | linux kernel | Versi 5.16 hingga sebelum 6.1.63 |
| linux | linux kernel | Versi 6.2 hingga sebelum 6.5.12 |
| linux | linux kernel | Versi 6.6 hingga sebelum 6.6.2 |