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 accumu...

Classification

CVE ID: CVE-2023-52854

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.08% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

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

Timeline