CVE-2024-39301 – This CVE describes an uninitialized value vulne... (How to Fix)

Q: What is the severity of CVE-2024-39301?

CVE-2024-39301 has a CVSS score of 5.5 (MEDIUM). This CVE describes an uninitialized value vulnerability in the Linux kernel's 9p filesystem client. When p9_check_errors() fails early in p9_client_rpc(), certain fields like 'tag' remain uninitialized but are later accessed by trace_9p_client_res(), potentially leaking kernel memory. This affects Linux systems using the 9p filesystem protocol.

📋 TL;DR

This CVE describes an uninitialized value vulnerability in the Linux kernel's 9p filesystem client. When p9_check_errors() fails early in p9_client_rpc(), certain fields like 'tag' remain uninitialized but are later accessed by trace_9p_client_res(), potentially leaking kernel memory. This affects Linux systems using the 9p filesystem protocol.

💻 Affected Systems

Products:

Linux kernel

Versions: Kernel versions with vulnerable 9p client implementation (specific versions not specified in CVE, but patches exist for stable branches)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable if 9p filesystem is enabled and in use. Many distributions don't enable 9p by default.

📦 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 memory information disclosure leading to potential privilege escalation or system compromise if combined with other vulnerabilities.

🟠

Likely Case

Information disclosure of uninitialized kernel memory, potentially exposing sensitive data or system state.

🟢

If Mitigated

No impact if the vulnerability is patched or 9p filesystem is not in use.

🌐 Internet-Facing: LOW - 9p filesystem is typically used in virtualization/container environments, not directly internet-exposed.

🏢 Internal Only: MEDIUM - Could be exploited by malicious containers or VMs in shared environments using 9p.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires access to trigger the 9p client error path and ability to read kernel memory traces.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in kernel stable releases via commits referenced in CVE

Vendor Advisory: https://git.kernel.org/stable/c/124947855564572713d705a13be7d0c9dae16a17

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. Reboot system to load new kernel. 3. Verify 9p functionality if used.

🔧 Temporary Workarounds

Disable 9p filesystem

linux

Prevent loading of 9p filesystem module if not required

echo 'install 9p /bin/false' >> /etc/modprobe.d/disable-9p.conf
rmmod 9p 2>/dev/null || true

🧯 If You Can't Patch

Disable 9p filesystem support in kernel configuration and rebuild
Restrict container/VM access to prevent triggering vulnerable code path

🔍 How to Verify

Check if Vulnerable:

Check if 9p module is loaded: lsmod | grep 9p. If loaded and kernel version is unpatched, system may be vulnerable.

Check Version:

uname -r

Verify Fix Applied:

Check kernel version includes fix commits: grep -q '124947855564572713d705a13be7d0c9dae16a17\|2101901dd58c6da4924bc5efb217a1d83436290b' /proc/version_signature 2>/dev/null || uname -r

📡 Detection & Monitoring

Log Indicators:

Kernel oops or KMSAN reports related to 9p client
Unexpected kernel memory access errors in system logs

Network Indicators:

9p protocol traffic to/from containers/VMs

SIEM Query:

source="kernel" AND ("9p" OR "p9_client") AND ("uninit" OR "KMSAN" OR "error")

📊 Metadata

CVE ID: CVE-2024-39301

CVSS v3 Score: 5.5 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-665

Published: June 25, 2024

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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