CVE-2022-50219
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's BPF subsystem allows attackers to trigger memory corruption when BPF links are detached under specific memory allocation failure conditions. This affects Linux systems using cgroup BPF functionality, potentially leading to kernel crashes or privilege escalation. The vulnerability requires local access to exploit.
💻 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 leading to system crash, or potential privilege escalation to root if an attacker can control the freed memory region.
Likely Case
Kernel crash causing system instability or denial of service, requiring reboot to restore functionality.
If Mitigated
Minimal impact if systems are patched or don't use cgroup BPF functionality extensively.
🎯 Exploit Status
Exploitation requires local access and ability to create/detach BPF links while triggering memory allocation failures. Syzbot found this through fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with fixes: 1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443, 3527e3cbb84d8868c4d4e91ba55915f96d39ec3d, 4c46091ee985ae84c60c5e95055d779fcd291d87, 6336388715afa419cc97d0255bda3bba1b96b7ca, be001f9da71eaa3b61e186fb88bde3279728bdca
Vendor Advisory: https://git.kernel.org/stable/c/1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443
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 after reboot.
🔧 Temporary Workarounds
Disable BPF subsystem
linuxDisable BPF functionality to prevent exploitation, but this will break applications relying on BPF.
echo 1 > /proc/sys/kernel/unprivileged_bpf_disabled
Remove BPF-related kernel modules if possible
Restrict cgroup BPF usage
linuxLimit which users can create BPF programs and links using cgroups.
Use cgroup permissions to restrict BPF operations to trusted users only
🧯 If You Can't Patch
- Restrict local user access to systems - only allow trusted users with legitimate needs
- Monitor for kernel crashes or unusual BPF/cgroup activity in system logs
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions from kernel git repository. Systems with unpatched kernels using BPF cgroup functionality are vulnerable.Check Version:
uname -rVerify Fix Applied:
Verify kernel version matches patched version after update and reboot. Check that BPF functionality still works correctly.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- KASAN error reports mentioning compute_effective_progs or BPF link operations
- System crashes or unexpected reboots
Network Indicators:
- None - local exploitation only
SIEM Query:
Search for kernel panic events, KASAN reports, or system crash logs with BPF/cgroup context🔗 References
- https://git.kernel.org/stable/c/1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443
- https://git.kernel.org/stable/c/3527e3cbb84d8868c4d4e91ba55915f96d39ec3d
- https://git.kernel.org/stable/c/4c46091ee985ae84c60c5e95055d779fcd291d87
- https://git.kernel.org/stable/c/6336388715afa419cc97d0255bda3bba1b96b7ca
- https://git.kernel.org/stable/c/be001f9da71eaa3b61e186fb88bde3279728bdca
