NULL Pointer Dereference Affecting kernel-rt-modules-internal package, versions *


Severity

Recommended
low

Based on CentOS security rating

    Threat Intelligence

    EPSS
    0.04% (12th percentile)

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  • Snyk ID SNYK-CENTOS8-KERNELRTMODULESINTERNAL-7328177
  • published 21 Jun 2024
  • disclosed 19 Jun 2024

How to fix?

There is no fixed version for Centos:8 kernel-rt-modules-internal.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules-internal package and not the kernel-rt-modules-internal package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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

ALSA: core: Fix NULL module pointer assignment at card init

The commit 81033c6b584b ("ALSA: core: Warn on empty module") introduced a WARN_ON() for a NULL module pointer passed at snd_card object creation, and it also wraps the code around it with '#ifdef MODULE'. This works in most cases, but the devils are always in details. "MODULE" is defined when the target code (i.e. the sound core) is built as a module; but this doesn't mean that the caller is also built-in or not. Namely, when only the sound core is built-in (CONFIG_SND=y) while the driver is a module (CONFIG_SND_USB_AUDIO=m), the passed module pointer is ignored even if it's non-NULL, and card->module remains as NULL. This would result in the missing module reference up/down at the device open/close, leading to a race with the code execution after the module removal.

For addressing the bug, move the assignment of card->module again out of ifdef. The WARN_ON() is still wrapped with ifdef because the module can be really NULL when all sound drivers are built-in.

Note that we keep 'ifdef MODULE' for WARN_ON(), otherwise it would lead to a false-positive NULL module check. Admittedly it won't catch perfectly, i.e. no check is performed when CONFIG_SND=y. But, it's no real problem as it's only for debugging, and the condition is pretty rare.

CVSS Scores

version 3.1
Expand this section

Red Hat

4.4 medium
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    High
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    None
  • Availability (A)
    High
Expand this section

SUSE

4.4 medium