CVE-2023-52446
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's BPF subsystem where a race condition between btf_put() and map_free() operations can lead to memory corruption. Attackers with local access can potentially exploit this to cause denial of service, escalate privileges, or execute arbitrary code. All systems running affected Linux kernel versions with BPF enabled are 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to root, arbitrary code execution in kernel context leading to complete system compromise.
Likely Case
Kernel panic or system crash causing denial of service, potentially leading to privilege escalation in sophisticated attacks.
If Mitigated
System instability or crashes if exploited, but limited by proper access controls and exploit complexity.
🎯 Exploit Status
Exploitation requires local access and knowledge of kernel internals. Race conditions can be challenging to reliably exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with commits: 59e5791f59dd83e8aa72a4e74217eabb6e8cfd90, d048dced8ea5eac6723ae873a40567e6f101ea42, f9ff6ef1c73cd9e1a6bb1ab3e57c5d141a536306
Vendor Advisory: https://git.kernel.org/stable/c/59e5791f59dd83e8aa72a4e74217eabb6e8cfd90
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution vendor. 2. For custom kernels, apply the referenced commits. 3. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
Disable BPF subsystem
linuxDisable the BPF subsystem to prevent exploitation, but this will break functionality that depends on BPF (eBPF programs, system monitoring tools, etc.)
Add 'bpf.maps_enable=0' to kernel boot parameters in GRUB configuration
Restrict BPF usage
linuxUse kernel lockdown mode or BPF LSM restrictions to limit who can use BPF
echo 1 > /proc/sys/kernel/kptr_restrict
Use BPF LSM: https://docs.kernel.org/bpf/linux.html
🧯 If You Can't Patch
- Implement strict access controls to limit local user accounts and prevent unauthorized local access
- Monitor for kernel crashes or suspicious BPF-related activity using system logs and auditd
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if BPF is enabled: 'uname -r' and 'grep CONFIG_BPF_SYSCALL /boot/config-$(uname -r)'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is updated to a version containing the fix commits, or test with the original reproducer from the CVE description📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- KASAN error messages mentioning 'slab-use-after-free' in bpf_rb_root_free
- System crashes or unexpected reboots
Network Indicators:
- Not applicable - local exploitation only
SIEM Query:
source="kernel" AND ("KASAN" OR "slab-use-after-free" OR "bpf_rb_root_free")🔗 References
- https://git.kernel.org/stable/c/59e5791f59dd83e8aa72a4e74217eabb6e8cfd90
- https://git.kernel.org/stable/c/d048dced8ea5eac6723ae873a40567e6f101ea42
- https://git.kernel.org/stable/c/f9ff6ef1c73cd9e1a6bb1ab3e57c5d141a536306
- https://git.kernel.org/stable/c/59e5791f59dd83e8aa72a4e74217eabb6e8cfd90
- https://git.kernel.org/stable/c/d048dced8ea5eac6723ae873a40567e6f101ea42
- https://git.kernel.org/stable/c/f9ff6ef1c73cd9e1a6bb1ab3e57c5d141a536306
