CVE-2022-50274
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's DVB (Digital Video Broadcasting) subsystem. When dvb_unregister_device() is called, it can free memory that is still being referenced by file pointers, potentially allowing attackers to execute arbitrary code or crash the system. This affects Linux systems using DVB devices, particularly media servers and set-top boxes.
💻 Affected Systems
- Linux kernel
📦 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 →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
Local privilege escalation to kernel-level access, allowing complete system compromise including data theft, persistence installation, or system destruction.
Likely Case
Kernel panic leading to system crash and denial of service, potentially requiring physical reboot.
If Mitigated
System remains stable with no impact if the vulnerability is not triggered or proper kernel protections are enabled.
🎯 Exploit Status
Requires local access and ability to interact with DVB devices. Exploitation would need to trigger the specific race condition during device unregistration.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79, 219b44bf94203bd433aa91b7796475bf656348e5, 2abd73433872194bccdf1432a0980e4ec5273c2a, 6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2, 88a6f8a72d167294c0931c7874941bf37a41b6dd
Vendor Advisory: https://git.kernel.org/stable/c/0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for specific patched kernel versions. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable DVB subsystem
linuxRemove or blacklist DVB kernel modules if not needed
echo 'blacklist dvb-core' >> /etc/modprobe.d/blacklist.conf
rmmod dvb-core
Restrict DVB device access
linuxLimit which users can access DVB devices
chmod 600 /dev/dvb/*
setfacl -m u:root:rw /dev/dvb/*
🧯 If You Can't Patch
- Restrict local user access to systems with DVB devices
- Implement strict privilege separation and limit who can load/unload kernel modules
🔍 How to Verify
Check if Vulnerable:
Check if DVB modules are loaded: lsmod | grep dvb. Check kernel version against distribution's patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version is updated to patched version and DVB modules show proper reference counting in kernel logs.📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages related to dvbdev
- System crashes after DVB device operations
- Unexpected kernel module unloading
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
source="kernel" AND ("dvb" OR "use-after-free" OR "general protection fault")🔗 References
- https://git.kernel.org/stable/c/0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79
- https://git.kernel.org/stable/c/219b44bf94203bd433aa91b7796475bf656348e5
- https://git.kernel.org/stable/c/2abd73433872194bccdf1432a0980e4ec5273c2a
- https://git.kernel.org/stable/c/6d18b44bb44e1f4d97dfe0efe92ac0f0984739c2
- https://git.kernel.org/stable/c/88a6f8a72d167294c0931c7874941bf37a41b6dd
- https://git.kernel.org/stable/c/9945d05d6693710574f354c5dbddc47f5101eb77
- https://git.kernel.org/stable/c/a2f0a08aa613176c9688c81d7b598a7779974991
- https://git.kernel.org/stable/c/ac521bbe3d00fa574e66a9361763f2b37725bc97
