CVE-2022-50036
📋 TL;DR
This CVE describes an integer underflow vulnerability in the Linux kernel's sun4i DRM DSI driver. When computing packet sizes with short sync pulses, unsigned arithmetic can underflow and wrap to large values, potentially causing kernel instability or crashes. This affects Linux systems using Allwinner (sun4i) display hardware.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic or system crash leading to denial of service, potentially allowing local privilege escalation if combined with other vulnerabilities.
Likely Case
System instability, display corruption, or kernel crashes when using affected Allwinner hardware with specific display configurations.
If Mitigated
Minimal impact with proper kernel hardening and restricted user access to display subsystems.
🎯 Exploit Status
Exploitation requires local access and ability to interact with display hardware. No public exploits have been reported.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 82a1356a933d8443139f8886f11b63c974a09a67, 98e28de472ef248352f04f87e29e634ebb0ec240, a1e7908f78f5a7f53f8cd83c7dcdfec974c95f26, fb837f5b83461624e525727a8f4add14b201147e
Vendor Advisory: https://git.kernel.org/stable/c/82a1356a933d8443139f8886f11b63c974a09a67
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable sun4i DSI driver
linuxPrevent loading of the vulnerable driver module
echo 'blacklist sun4i-drm' > /etc/modprobe.d/blacklist-sun4i.conf
update-initramfs -u
reboot
🧯 If You Can't Patch
- Restrict local user access to systems with Allwinner hardware
- Implement kernel hardening measures like SELinux/AppArmor to limit driver access
🔍 How to Verify
Check if Vulnerable:
Check if sun4i-drm module is loaded: lsmod | grep sun4i. Check kernel version against distribution security advisories.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits. Check dmesg for sun4i driver errors after fix.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- DRM/sun4i driver crash logs
- Display subsystem errors
Network Indicators:
- None - this is a local driver vulnerability
SIEM Query:
source="kernel" AND ("sun4i" OR "drm" OR "display") AND ("panic" OR "crash" OR "underflow")