CVE-2023-53021
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's taprio scheduler (sch_taprio) allows local attackers to cause a kernel crash or potentially execute arbitrary code. The vulnerability occurs when destroying a taprio qdisc while its timer is still active, leading to memory corruption. This affects Linux systems using the taprio scheduler.
💻 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 →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 potential privilege escalation to kernel-level code execution.
Likely Case
Kernel crash causing system instability or denial of service.
If Mitigated
Limited to denial of service if proper kernel hardening prevents code execution.
🎯 Exploit Status
Requires local access and ability to configure taprio qdisc with invalid parameters. Exploitation requires specific timing conditions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 1200388a0b1c3c6fda48d4d2143db8f7e4ef5348, 3a415d59c1dbec9d772dbfab2d2520d98360caae, c53acbf2facfdfabdc6e6984a1a38f5d38b606a1, c60fe70078d6e515f424cb868d07e00411b27fbc, d3b2d2820a005e43855fa71b80c4a4b194201c60
Vendor Advisory: https://git.kernel.org/stable/c/1200388a0b1c3c6fda48d4d2143db8f7e4ef5348
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for backported patches. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable taprio scheduler
allPrevent use of vulnerable taprio qdisc by removing or not configuring it.
# Remove any taprio qdisc configurations
# Check with: tc qdisc show
# Remove with: tc qdisc del dev <interface> root
Restrict taprio configuration
allLimit who can configure network qdiscs using capabilities or sudo restrictions.
# Remove CAP_NET_ADMIN from non-privileged users
# Use sudoers to restrict tc command access
🧯 If You Can't Patch
- Restrict local user access to systems
- Implement strict capability controls (remove CAP_NET_ADMIN from non-admin users)
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if taprio is configured: uname -r && tc qdisc show | grep taprioCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or check with distribution's security advisory.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- KMSAN error messages in dmesg
- System crashes with net_tx_action stack traces
Network Indicators:
- Unusual taprio configuration attempts
SIEM Query:
Search for: 'KMSAN: uninit-value' OR 'net_tx_action' OR 'taprio_destroy' in kernel logs🔗 References
- https://git.kernel.org/stable/c/1200388a0b1c3c6fda48d4d2143db8f7e4ef5348
- https://git.kernel.org/stable/c/3a415d59c1dbec9d772dbfab2d2520d98360caae
- https://git.kernel.org/stable/c/c53acbf2facfdfabdc6e6984a1a38f5d38b606a1
- https://git.kernel.org/stable/c/c60fe70078d6e515f424cb868d07e00411b27fbc
- https://git.kernel.org/stable/c/d3b2d2820a005e43855fa71b80c4a4b194201c60
