CVE-2024-56675
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's BPF subsystem where uprobes use tasks-trace-RCU protection while non-sleepable BPF programs are freed via normal RCU. This mismatch allows an attacker to potentially execute arbitrary code with kernel privileges. Any system running an affected Linux kernel version with BPF enabled is vulnerable.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to root, kernel memory corruption leading to system crash or persistent compromise.
Likely Case
Local privilege escalation allowing attackers to gain root access on vulnerable systems.
If Mitigated
Limited impact if BPF is disabled or systems are properly segmented with minimal local user access.
🎯 Exploit Status
Exploitation requires local access and knowledge of BPF subsystem. The vulnerability is in RCU synchronization logic which requires precise timing to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (commits: 9245459a992d22fe0e92e988f49db1fec82c184a, 9b53d2c2a38a1effc341d99be3f99fa7ef17047d, ef1b808e3b7c98612feceedf985c2fbbeb28f956, f9f85df30118f3f4112761e6682fc60ebcce23e5)
Vendor Advisory: https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution vendor. 2. For Debian systems, apply security updates via apt. 3. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
Disable BPF subsystem
linuxDisable the BPF subsystem to prevent exploitation (may break functionality)
echo 'kernel.unprivileged_bpf_disabled=2' >> /etc/sysctl.conf
sysctl -p
Restrict BPF usage
linuxLimit BPF functionality to privileged users only
echo 'kernel.unprivileged_bpf_disabled=1' >> /etc/sysctl.conf
sysctl -p
🧯 If You Can't Patch
- Implement strict access controls to limit local user access to vulnerable systems
- Monitor for privilege escalation attempts and unusual BPF program activity
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if patches are applied. Vulnerable if running unpatched kernel with BPF enabled.Check Version:
uname -rVerify Fix Applied:
Verify kernel version matches patched version from your distribution. Check that the specific commit hashes are present in kernel source.📡 Detection & Monitoring
Log Indicators:
- Failed privilege escalation attempts
- Unusual BPF program loading
- Kernel panic or oops messages
Network Indicators:
- None - this is a local exploit
SIEM Query:
Process monitoring for suspicious BPF program execution or privilege escalation patterns🔗 References
- https://git.kernel.org/stable/c/9245459a992d22fe0e92e988f49db1fec82c184a
- https://git.kernel.org/stable/c/9b53d2c2a38a1effc341d99be3f99fa7ef17047d
- https://git.kernel.org/stable/c/ef1b808e3b7c98612feceedf985c2fbbeb28f956
- https://git.kernel.org/stable/c/f9f85df30118f3f4112761e6682fc60ebcce23e5
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
