CVE-2025-21847
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's Sound Open Firmware (SOF) subsystem could cause kernel crashes or denial of service. This affects systems using SOF for audio processing, primarily Linux servers and workstations with specific audio hardware configurations. The vulnerability occurs when the sof_ipc_msg_data() function fails to properly validate a pointer before dereferencing it.
💻 Affected Systems
- Linux kernel with Sound Open Firmware (SOF) subsystem
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
Local denial of service through kernel crash when specific audio operations are performed by privileged users or processes.
If Mitigated
Minimal impact with proper privilege separation and audio subsystem restrictions.
🎯 Exploit Status
Requires local access and ability to trigger specific audio operations. Likely requires root or audio group privileges.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel versions containing commits 2b3878baf90918a361a3dfd3513025100b1b40b6, 62ab1ae5511c59b5f0bf550136ff321331adca9f, 6c18f5eb2043ebf4674c08a9690218dc818a11ab, or d8d99c3b5c485f339864aeaa29f76269cc0ea975
Vendor Advisory: https://git.kernel.org/stable/c/2b3878baf90918a361a3dfd3513025100b1b40b6
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version matches patched release.
🔧 Temporary Workarounds
Disable SOF subsystem
linuxPrevent loading of SOF modules if audio functionality is not required
echo 'blacklist snd-sof' >> /etc/modprobe.d/blacklist.conf
echo 'blacklist snd-sof-pci' >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
Restrict audio device access
linuxLimit which users can access audio devices to reduce attack surface
chmod 660 /dev/snd/*
chown root:audio /dev/snd/*
🧯 If You Can't Patch
- Implement strict privilege separation to limit which users can access audio devices and perform audio operations.
- Monitor system logs for kernel panic events and implement automated alerting for system instability.
🔍 How to Verify
Check if Vulnerable:
Check if SOF modules are loaded: lsmod | grep -E 'snd_sof|snd_sof_pci'. Check kernel version against distribution's security advisories.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits. Check dmesg for SOF-related errors after audio operations.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- NULL pointer dereference errors mentioning sof_ipc_msg_data
- Audio subsystem crash logs
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "kernel panic") AND ("sof" OR "audio")