CVE-2024-49884
📋 TL;DR
This is a use-after-free vulnerability in the Linux kernel's ext4 filesystem driver that allows attackers to potentially crash the system or execute arbitrary code with kernel privileges. It affects Linux systems using the ext4 filesystem when specific error conditions occur during extent splitting operations. The vulnerability requires local access to trigger.
💻 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 →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 denial of service, or potential privilege escalation to root via arbitrary code execution in kernel context.
Likely Case
System crash or kernel panic causing denial of service, potentially requiring physical or remote console access to reboot.
If Mitigated
Limited impact if system has proper access controls preventing unprivileged users from triggering the specific filesystem operations.
🎯 Exploit Status
Requires local access and ability to trigger specific filesystem operations that cause memory allocation or I/O errors during extent splitting.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in kernel commits: 393a46f60ea4f249dc9d496d4eb2d542f5e11ade, 448100a29395b0c8b4c42967155849fe0fbe808f, 5d949ea75bb529ea6342e83465938a3b0ac51238, 8fe117790b37c84c651e2bad9efc0e7fda73c0e3, 915ac3630488af0ca194dc63b86d99802b4f6e18
Vendor Advisory: https://git.kernel.org/stable/c/393a46f60ea4f249dc9d496d4eb2d542f5e11ade
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution. 2. For custom kernels, apply the referenced git commits. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable ext4 filesystem use
linuxUse alternative filesystems like XFS or Btrfs instead of ext4
# Format partitions with alternative filesystem
# Update /etc/fstab to use non-ext4 filesystems
Restrict user access to filesystem operations
linuxLimit user permissions to reduce chance of triggering the vulnerability
# Use appropriate file permissions and access controls
# Implement SELinux/AppArmor policies to restrict filesystem operations
🧯 If You Can't Patch
- Implement strict access controls to limit which users can perform filesystem operations
- Monitor system logs for kernel panics or KASAN reports related to ext4 operations
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if ext4 is in use: uname -r and check /etc/fstab for ext4 partitionsCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated beyond vulnerable commits and check for absence of ext4-related kernel panics📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- KASAN reports mentioning ext4_split_extent_at
- System crashes during filesystem operations
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for kernel logs containing 'KASAN: slab-use-after-free', 'ext4_split_extent_at', or 'kernel panic'🔗 References
- https://git.kernel.org/stable/c/393a46f60ea4f249dc9d496d4eb2d542f5e11ade
- https://git.kernel.org/stable/c/448100a29395b0c8b4c42967155849fe0fbe808f
- https://git.kernel.org/stable/c/5d949ea75bb529ea6342e83465938a3b0ac51238
- https://git.kernel.org/stable/c/8fe117790b37c84c651e2bad9efc0e7fda73c0e3
- https://git.kernel.org/stable/c/915ac3630488af0ca194dc63b86d99802b4f6e18
- https://git.kernel.org/stable/c/a5401d4c3e2a3d25643c567d26e6de327774a2c9
- https://git.kernel.org/stable/c/c26ab35702f8cd0cdc78f96aa5856bfb77be798f
- https://git.kernel.org/stable/c/cafcc1bd62934547c76abf46c6d0d54f135006fe
- https://git.kernel.org/stable/c/e52f933598b781d291b9297e39c463536da0e185
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
- https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html
