CVE-2021-47643
📋 TL;DR
This CVE describes a memory leak vulnerability in the Linux kernel's IR Toy driver (media: ir_toy). The driver fails to properly free allocated memory before exiting on error paths, potentially leading to resource exhaustion. This affects Linux systems using the IR Toy infrared receiver 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
Sustained exploitation could lead to kernel memory exhaustion, causing system instability, denial of service, or kernel panic.
Likely Case
Local users could trigger the memory leak repeatedly, gradually consuming kernel memory and potentially degrading system performance over time.
If Mitigated
With proper access controls, only privileged users could trigger the vulnerability, limiting impact to authorized personnel.
🎯 Exploit Status
Exploitation requires local access and ability to interact with the IR Toy device driver. No public exploits have been documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing the fix commits: 2011363c196846c083649c91ed30aeef64358d52, 382e0f6958ef34eb093127b6d74c12f3b8fd0904, 52cdb013036391d9d87aba5b4fc49cdfc6ea4b23, 93ef3fdf3b6633c58f049e5a6be755777dde4340, 99e3f83539cac6884a4df02cb204a57a184ea12b
Vendor Advisory: https://git.kernel.org/stable/c/2011363c196846c083649c91ed30aeef64358d52
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Reboot system to load new kernel. 3. Verify IR Toy driver is no longer vulnerable.
🔧 Temporary Workarounds
Disable IR Toy driver
linuxPrevent loading of the vulnerable IR Toy driver module
echo 'blacklist ir_toy' >> /etc/modprobe.d/blacklist-ir_toy.conf
rmmod ir_toy
Restrict device access
linuxLimit access to the IR Toy device to prevent exploitation
chmod 600 /dev/ir_toy_device
setfacl -m u:root:rw /dev/ir_toy_device
🧯 If You Can't Patch
- Restrict physical and local access to systems with IR Toy hardware
- Monitor kernel memory usage for unusual patterns indicating potential exploitation
🔍 How to Verify
Check if Vulnerable:
Check if IR Toy driver is loaded: lsmod | grep ir_toy. Check kernel version against affected versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits. Test IR Toy functionality to ensure no memory leaks occur.📡 Detection & Monitoring
Log Indicators:
- Kernel oom-killer messages
- Unusual memory consumption patterns in /var/log/kern.log
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
source="kern.log" AND ("out of memory" OR "oom-killer") AND process="ir_toy"🔗 References
- https://git.kernel.org/stable/c/2011363c196846c083649c91ed30aeef64358d52
- https://git.kernel.org/stable/c/382e0f6958ef34eb093127b6d74c12f3b8fd0904
- https://git.kernel.org/stable/c/52cdb013036391d9d87aba5b4fc49cdfc6ea4b23
- https://git.kernel.org/stable/c/93ef3fdf3b6633c58f049e5a6be755777dde4340
- https://git.kernel.org/stable/c/99e3f83539cac6884a4df02cb204a57a184ea12b
