ALSA: seq: Fix race of snd_seq_timer_open() in Kernel
Summary
GSD-2021-1001018: ALSA: seq: Fix race of snd_seq_timer_open(). Affects Kernel versions < 536a7646c00a0f14fee49e5e313109e5da2f6031. No fix is published. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
The Kernel is a fundamental component of the Linux operating system that provides core functionalities and interfaces with hardware devices. It manages system resources, facilitates communication between software and hardware, and ensures the stability and security of the system. One of the components of the Kernel is ALSA (Advanced Linux Sound Architecture), which provides audio and MIDI functionality. ALSA includes a sequencer subsystem (snd_seq) that allows applications to send and receive MIDI events. However, a race condition vulnerability has been discovered in the snd_seq_timer_open() function of the ALSA seq subsystem.
Vulnerability Detail
The race condition vulnerability in snd_seq_timer_open() can be exploited by an attacker to cause a denial-of-service (DoS) condition or potentially execute arbitrary code with kernel privileges. The vulnerability arises due to improper synchronization when accessing the timer list, which can lead to a double-free or use-after-free scenario. An attacker could exploit this vulnerability by sending specially crafted MIDI events to a vulnerable system, triggering the race condition and potentially gaining control over the system.
How To Fix
No fixed version is published for this vulnerability.
Tip — Not sure whether your app is affected? Vulert can check the versions your app actually runs. Scan free →
Workaround
As a workaround, users can disable the ALSA seq subsystem by blacklisting the 'snd_seq' module. This can be achieved by adding the following line to the '/etc/modprobe.d/blacklist.conf' file:
blacklist snd_seq
After adding the blacklist entry, restart the system to apply the changes. However, this workaround will disable the ALSA sequencer functionality, which may impact applications relying on MIDI functionality.
Conclusion
The race condition vulnerability in snd_seq_timer_open() of the ALSA seq subsystem in the Linux Kernel can lead to a denial-of-service (DoS) condition or potential execution of arbitrary code with kernel privileges. It is crucial to update the Kernel to version v5.12.11 or later to mitigate this vulnerability. Additionally, users can apply the workaround of blacklisting the 'snd_seq' module, although this will disable ALSA sequencer functionality. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for Kernel →
FAQ
The vulnerability can lead to a denial-of-service (DoS) condition or potential execution of arbitrary code with kernel privileges. An attacker could exploit this vulnerability to gain control over the affected system.
You can use the Vulert Playground (https://vulert.com/scanner) to check if your system is affected by this vulnerability. Simply upload your package-lock.json file to the playground, and it will analyze the dependencies and alert you if any known vulnerabilities are present.
Yes, a patch for this vulnerability is available in the Linux Kernel version v5.12.11. It is recommended to update your Kernel installation to the latest stable version to apply the fix.
Yes, a workaround is to disable the ALSA seq subsystem by blacklisting the 'snd_seq' module. However, this will disable the ALSA sequencer functionality, which may impact applications relying on MIDI functionality.
You can find more information about this vulnerability in the GSD-2021-1001018 JSON file available in the GSD database repository: https://github.com/cloudsecurityalliance/gsd-database/blob/main/2021/1001xxx/GSD-2021-1001018.json
Related vulnerabilities
Recent vulnerabilities recorded for Kernel.
