Red Hat: CVE-2024-38605: kernel: ALSA: core: Fix NULL module pointer assignment at card init (Multiple Advisories)

Red Hat: CVE-2024-38605: kernel: ALSA: core: Fix NULL module pointer assignment at card init (Multiple Advisories)

Severity

4

CVSS

(AV:L/AC:L/Au:M/C:N/I:N/A:C)

Published

06/19/2024

Created

12/06/2024

Added

12/05/2024

Modified

12/05/2024

Description

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.

Solution(s)

• redhat-upgrade-kernel
• redhat-upgrade-kernel-rt

References

• CVE-2024-38605
• RHSA-2024:9315