CVE-2024-56764
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's ublk subsystem allows attackers to potentially crash the kernel or execute arbitrary code with kernel privileges. This affects Linux systems using the ublk driver for userspace block devices. Attackers need local access to exploit this vulnerability.
💻 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
Kernel panic leading to system crash or arbitrary code execution with kernel privileges, potentially resulting in complete system compromise.
Likely Case
Kernel panic causing system crash and denial of service, requiring physical or remote console access to reboot.
If Mitigated
No impact if the system is not using ublk driver or has been patched.
🎯 Exploit Status
Requires local access and ability to trigger ublk operations that cause add_disk() to fail followed by abort requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel commits 75cd4005da5492129917a4a4ee45e81660556104 and 7d680f2f76a3417fdfc3946da7471e81464f7b41
Vendor Advisory: https://git.kernel.org/stable/c/75cd4005da5492129917a4a4ee45e81660556104
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check with your distribution for backported patches. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable ublk module
allPrevent loading of the vulnerable ublk driver
echo 'install ublk /bin/false' > /etc/modprobe.d/ublk.conf
rmmod ublk 2>/dev/null || true
Blacklist ublk module
allBlacklist the ublk kernel module to prevent loading
echo 'blacklist ublk' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Ensure ublk module is not loaded (check with 'lsmod | grep ublk')
- Restrict local user access to systems using mandatory access controls like SELinux or AppArmor
🔍 How to Verify
Check if Vulnerable:
Check if ublk module is loaded: 'lsmod | grep ublk'. If loaded and kernel version is unpatched, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
Check kernel version includes fix commits or verify ublk module is not loaded: 'lsmod | grep -q ublk && echo "Vulnerable" || echo "Fixed/Not vulnerable"'📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages in /var/log/kern.log or dmesg
- System crashes or reboots without clear cause
Network Indicators:
- None - local exploitation only
SIEM Query:
EventID=41 OR Source="Linux Kernel" AND (Message="Oops" OR Message="general protection fault")