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NULL Pointer Dereference Affecting kernel-64k-debug-devel package, versions <0:5.14.0-427.31.1.el9_4

Severity

 Recommended
high

Based on AlmaLinux security rating

    Threat Intelligence

    EPSS
    0.04% (6th percentile)

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  • Snyk ID SNYK-ALMALINUX9-KERNEL64KDEBUGDEVEL-8331970
  • published 4 Nov 2024
  • disclosed 14 Aug 2024
Report a new vulnerability Found a mistake?

Introduced: 14 Aug 2024

CVE-2024-36489 Open this link in a new tab
CWE-476 Open this link in a new tab

How to fix?

Upgrade AlmaLinux:9 kernel-64k-debug-devel to version 0:5.14.0-427.31.1.el9_4 or higher.
This issue was patched in ALSA-2024:5363.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-debug-devel package and not the kernel-64k-debug-devel package as distributed by AlmaLinux. See How to fix? for AlmaLinux: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.

References

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