CVE-2022-48689
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's TCP zerocopy implementation where the kernel incorrectly checks pfmemalloc page status for user-space pages. This can cause false positives leading to potential memory corruption or system instability. It affects Linux systems using TCP zerocopy functionality.
💻 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, system crash, or memory corruption leading to privilege escalation or denial of service.
Likely Case
System instability, kernel crashes, or performance degradation under specific network conditions.
If Mitigated
Minor performance impact or no noticeable effect with proper kernel versions.
🎯 Exploit Status
Exploitation requires precise timing (race condition) and specific network conditions. Found via syzbot fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 3261400639463a853ba2b3be8bd009c2a8089775, 6730c48ed6b0cd939fc9b30b2d621ce0b89bea83, 8527c9a6bf8e54fef0a8d3d7d8874a48c725c915
Vendor Advisory: https://git.kernel.org/stable/c/3261400639463a853ba2b3be8bd009c2a8089775
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing fix commits. 2. For stable teams: backport 84ce071e38a6 (net: introduce __skb_fill_page_desc_noacc) as prerequisite. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable TCP zerocopy
linuxDisable TCP zerocopy functionality to prevent the vulnerable code path
sysctl -w net.ipv4.tcp_zerocopy_receive=0
🧯 If You Can't Patch
- Disable TCP zerocopy functionality via sysctl
- Implement network segmentation to limit exposure
- Monitor system logs for kernel panics or instability
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if TCP zerocopy is enabled: sysctl net.ipv4.tcp_zerocopy_receiveCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits and TCP zerocopy works without issues📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- System crash dumps
- KCSAN race condition reports in dmesg
Network Indicators:
- TCP connection resets
- Network performance degradation
SIEM Query:
source="kernel" AND ("panic" OR "KCSAN" OR "race condition")🔗 References
- https://git.kernel.org/stable/c/3261400639463a853ba2b3be8bd009c2a8089775
- https://git.kernel.org/stable/c/6730c48ed6b0cd939fc9b30b2d621ce0b89bea83
- https://git.kernel.org/stable/c/8527c9a6bf8e54fef0a8d3d7d8874a48c725c915
- https://git.kernel.org/stable/c/3261400639463a853ba2b3be8bd009c2a8089775
- https://git.kernel.org/stable/c/6730c48ed6b0cd939fc9b30b2d621ce0b89bea83
- https://git.kernel.org/stable/c/8527c9a6bf8e54fef0a8d3d7d8874a48c725c915
