CVE-2023-53366
📋 TL;DR
A NULL pointer dereference vulnerability in the Linux kernel's block layer when using polled I/O can cause kernel crashes. This occurs when two tasks share a poll queue and one completes I/O for the other, leading to a bio structure with a NULL bdev pointer being accessed. Systems using polled I/O (like io_uring) with affected kernel versions are vulnerable.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
System crash or kernel panic when polled I/O operations are performed concurrently by multiple tasks sharing poll queues.
If Mitigated
No impact if patched or if polled I/O is not used.
🎯 Exploit Status
Exploitation requires local access and ability to perform polled I/O operations. Race condition makes timing-dependent.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 0510d5e654d05053ed0e6309a9b42043ac9903ab, 1af0bdca03f367874da45d6cbe05fa05b90b1439, 310726c33ad76cebdee312dbfafc12c1b44bf977
Vendor Advisory: https://git.kernel.org/stable/c/0510d5e654d05053ed0e6309a9b42043ac9903ab
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check with your distribution for specific patched kernel versions. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable polled I/O
allAvoid using polled I/O features like io_uring polled mode to prevent triggering the vulnerability.
# Configure applications to not use polled I/O
# Review and modify io_uring configurations if used
🧯 If You Can't Patch
- Restrict local user access to minimize risk of exploitation.
- Monitor system logs for kernel panic or crash indicators and have recovery procedures ready.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if polled I/O is used. Vulnerable if kernel is before fix commits and polled I/O is enabled.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits (e.g., check git log or distribution patch notes).📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/messages or dmesg
- NULL pointer dereference errors related to bio_poll or block layer
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for kernel panic or Oops messages in system logs with references to bio_poll or block layer.