CVE-2021-47046
📋 TL;DR
This CVE describes an off-by-one buffer overflow vulnerability in the Linux kernel's AMD display driver. The flaw allows reading one byte beyond the allocated buffer in the HDCP authentication process, potentially leading to kernel memory disclosure or system crashes. Systems running affected Linux kernel versions with AMD graphics hardware are vulnerable.
💻 Affected Systems
- Linux kernel with AMD display driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel memory disclosure leading to information leakage, privilege escalation, or system crash/DoS
Likely Case
System instability or crash when HDCP authentication is attempted with AMD graphics
If Mitigated
No impact if patched or HDCP functionality is disabled
🎯 Exploit Status
Requires local access to trigger HDCP authentication process
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing the referenced git commits
Vendor Advisory: https://git.kernel.org/stable/c/080bd41d6478a64edf96704fddcda52b1fd5fed7
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version 2. Reboot system 3. Verify kernel version matches patched release
🔧 Temporary Workarounds
Disable HDCP functionality
linuxPrevent HDCP authentication which triggers the vulnerable code path
echo 0 > /sys/module/amdgpu/parameters/hdcp_enable
🧯 If You Can't Patch
- Restrict local user access to systems with AMD graphics
- Disable AMD graphics driver or use alternative graphics hardware
🔍 How to Verify
Check if Vulnerable:
Check kernel version against affected ranges and verify AMD graphics driver is loadedCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the referenced git commit hashes📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- AMD display driver crashes
- HDCP authentication failures
SIEM Query:
source="kernel" AND ("amdgpu" OR "HDCP" OR "display") AND ("panic" OR "oops" OR "segfault")🔗 References
- https://git.kernel.org/stable/c/080bd41d6478a64edf96704fddcda52b1fd5fed7
- https://git.kernel.org/stable/c/403c4528e5887af3deb9838cb77a557631d1e138
- https://git.kernel.org/stable/c/6a58310d5d1e5b02d0fc9b393ba540c9367bced5
- https://git.kernel.org/stable/c/8e6fafd5a22e7a2eb216f5510db7aab54cc545c1
- https://git.kernel.org/stable/c/080bd41d6478a64edf96704fddcda52b1fd5fed7
- https://git.kernel.org/stable/c/403c4528e5887af3deb9838cb77a557631d1e138
- https://git.kernel.org/stable/c/6a58310d5d1e5b02d0fc9b393ba540c9367bced5
- https://git.kernel.org/stable/c/8e6fafd5a22e7a2eb216f5510db7aab54cc545c1
