Resource Leak Affecting kernel-core package, versions <0:5.14.0-284.75.1.el9_2


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating

    Threat Intelligence

    EPSS
    0.04% (6th percentile)

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  • Snyk ID SNYK-RHEL9-KERNELCORE-7563787
  • published 25 Jul 2024
  • disclosed 21 Jun 2024

How to fix?

Upgrade RHEL:9 kernel-core to version 0:5.14.0-284.75.1.el9_2 or higher.
This issue was patched in RHSA-2024:4823.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-core package and not the kernel-core package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

tls: fix missing memory barrier in tls_init

In tls_init(), a write memory barrier is missing, and store-store reordering may cause NULL dereference in tls_{setsockopt,getsockopt}.

CPU0 CPU1


// In tls_init() // In tls_ctx_create() ctx = kzalloc() ctx->sk_proto = READ_ONCE(sk->sk_prot) -(1)

// In update_sk_prot() WRITE_ONCE(sk->sk_prot, tls_prots) -(2)

                               // In sock_common_setsockopt()
                               READ_ONCE(sk-&gt;sk_prot)-&gt;setsockopt()

                           // In tls_{setsockopt,getsockopt}()
                           ctx-&amp;gt;sk_proto-&amp;gt;setsockopt()    -(3)

In the above scenario, when (1) and (2) are reordered, (3) can observe the NULL value of ctx->sk_proto, causing NULL dereference.

To fix it, we rely on rcu_assign_pointer() which implies the release barrier semantic. By moving rcu_assign_pointer() after ctx->sk_proto is initialized, we can ensure that ctx->sk_proto are visible when changing sk->sk_prot.

CVSS Scores

version 3.1
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NVD

5.5 medium
  • 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

6.1 medium
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SUSE

4.7 medium