CVE-2023-52779
📋 TL;DR
A Linux kernel vulnerability in filesystem attribute handling causes a NULL pointer dereference when vfs_getattr_nosec() incorrectly calls vfs_getattr() instead of propagating the 'nosec' flag. This affects Linux systems using overlayfs or ecryptfs filesystems, potentially causing kernel crashes and denial of service.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, requiring physical or remote console access to reboot.
Likely Case
Local denial of service through kernel crash when specific filesystem operations are performed on overlayfs/ecryptfs.
If Mitigated
Minimal impact with proper kernel hardening and restricted user access to affected filesystem operations.
🎯 Exploit Status
Requires local access and knowledge of triggering conditions; primarily a reliability issue rather than privilege escalation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 3fb0fa08641903304b9d81d52a379ff031dc41d4 and 8a924db2d7b5eb69ba08b1a0af46e9f1359a9bdf
Vendor Advisory: https://git.kernel.org/stable/c/3fb0fa08641903304b9d81d52a379ff031dc41d4
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from distribution vendor. 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable overlayfs/ecryptfs
linuxAvoid using overlayfs or ecryptfs filesystems if not required.
# Check if overlayfs is mounted: mount | grep overlay
# Unmount overlayfs if present: umount /path/to/overlay
🧯 If You Can't Patch
- Restrict user access to filesystem operations that trigger getattr calls on overlayfs/ecryptfs.
- Implement kernel crash monitoring and automated recovery procedures.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and verify if overlayfs/ecryptfs are in use: uname -r && mount | grep -E 'overlay|ecryptfs'Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or is newer than patched version from vendor.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- NULL pointer dereference errors in system logs
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "kernel panic")