CVE-2023-53224
📋 TL;DR
This is a kernel control flow integrity (CFI) violation in the Linux kernel's ext4 filesystem module. When ext4 is built as a loadable module and unloaded with Clang's kCFI enabled, a function prototype mismatch causes a kernel panic or thread termination. Only systems with specific configurations are affected.
💻 Affected Systems
- Linux kernel with ext4 filesystem support
📦 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 →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 when unloading the ext4 module with kCFI enabled.
Likely Case
Thread termination or kernel panic during module unloading, causing service disruption but not privilege escalation.
If Mitigated
No impact if kCFI is disabled or ext4 is built into the kernel rather than as a module.
🎯 Exploit Status
Exploitation requires local privileged access to trigger module unloading. This is a reliability/DoS issue, not a privilege escalation vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check stable kernel trees (5.10.y, 5.15.y, 6.1.y, etc.) for commits containing the fix.
Vendor Advisory: https://git.kernel.org/stable/c/0a1394e07c5d6bf1bfc25db8589ff1b1bfb6f46a
Restart Required: No
Instructions:
1. Update to a patched kernel version from your distribution. 2. Rebuild kernel if using custom build. 3. No reboot required if using live kernel update mechanisms.
🔧 Temporary Workarounds
Disable kCFI
allBuild kernel without CONFIG_CFI_CLANG to avoid the CFI check that triggers the issue.
In kernel config: CONFIG_CFI_CLANG=n
Build ext4 as built-in
allCompile ext4 support directly into the kernel instead of as a loadable module.
In kernel config: CONFIG_EXT4_FS=y (not =m)
🧯 If You Can't Patch
- Avoid unloading ext4 kernel module if it's loaded as a module.
- Ensure systems don't have CONFIG_CFI_CLANG enabled in kernel configuration.
🔍 How to Verify
Check if Vulnerable:
Check kernel config for CONFIG_CFI_CLANG and if ext4 is built as module: grep -E 'CONFIG_CFI_CLANG|CONFIG_EXT4_FS' /boot/config-$(uname -r)Check Version:
uname -rVerify Fix Applied:
Check kernel version is patched: uname -r and verify with distribution's security advisory.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages mentioning 'CFI failure' or 'kobject_put' during module unloading
- System logs showing unexpected crashes when unloading ext4 module
Network Indicators:
- None - this is a local kernel issue
SIEM Query:
Search for kernel panic events with 'CFI' or 'ext4' in crash logs🔗 References
- https://git.kernel.org/stable/c/0a1394e07c5d6bf1bfc25db8589ff1b1bfb6f46a
- https://git.kernel.org/stable/c/118901ad1f25d2334255b3d50512fa20591531cd
- https://git.kernel.org/stable/c/1ba10d3640e9783dad811fe4e24d55465c37c64d
- https://git.kernel.org/stable/c/2b69cdd9f9a7f596e3dd31f05f9852940d177924
- https://git.kernel.org/stable/c/94d8de83286fb1827340eba35b61c308f6b46ead
- https://git.kernel.org/stable/c/99e3fd21f8fc975c95e8cf76fbf6a3d2656f8f71
- https://git.kernel.org/stable/c/c98077f7598a562f51051eec043be0cb3e1b1b5e
