CVE-2023-52854 Affecting kernel-rt-kvm package, versions *


Severity

low

    Threat Intelligence

    EPSS
    0.04% (11th percentile)

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  • Snyk ID SNYK-CENTOS7-KERNELRTKVM-7077800
  • published 23 May 2024
  • disclosed 21 May 2024

Introduced: 21 May 2024

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How to fix?

There is no fixed version for Centos:7 kernel-rt-kvm.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-kvm package and not the kernel-rt-kvm package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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:

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:

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 Scores

version 3.1
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Snyk

5.5 low
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    None
  • Availability (A)
    High
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Red Hat

5.5 medium
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SUSE

5.5 medium