CVE-2024-44971
📋 TL;DR
This CVE describes a memory leak vulnerability in the Linux kernel's Broadcom StrataSwitch DSA driver. The bcm_sf2_mdio_register() function fails to properly decrement reference counts when removing PHY devices, causing kernel memory to be consumed over time. This affects systems using Broadcom StrataSwitch-based networking hardware with the affected kernel driver.
💻 Affected Systems
- Linux kernel with bcm_sf2 DSA driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Sustained exploitation could lead to kernel memory exhaustion, causing system instability, denial of service, or kernel panic.
Likely Case
Gradual memory consumption over time leading to performance degradation and eventual system instability requiring reboot.
If Mitigated
Minimal impact with proper monitoring and regular reboots; memory leak rate depends on PHY device discovery frequency.
🎯 Exploit Status
This is a reliability issue rather than a security bypass. Exploitation requires triggering the specific code path repeatedly, which typically requires local access and specific hardware conditions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 7feef10768ea71d468d9bbc1e0d14c461876768c, a7d2808d67570e6acae45c2a96e0d59986888e4c, b7b8d9f5e679af60c94251fd6728dde34be69a71, c05516c072903f6fb9134b8e7e1ad4bffcdc4819, e3862093ee93fcfbdadcb7957f5f8974fffa806a
Vendor Advisory: https://git.kernel.org/stable/c/7feef10768ea71d468d9bbc1e0d14c461876768c
Restart Required: Yes
Instructions:
1. Update to a patched kernel version from your distribution vendor. 2. Reboot the system to load the new kernel. 3. Verify the fix by checking kernel version and monitoring memory usage.
🔧 Temporary Workarounds
Disable bcm_sf2 driver
linuxBlacklist or disable the affected driver if not required
echo 'blacklist bcm_sf2' >> /etc/modprobe.d/blacklist.conf
update-initramfs -u
reboot
Regular system monitoring and reboots
linuxMonitor kernel memory usage and schedule regular reboots
# Monitor slab memory: cat /proc/meminfo | grep Slab
# Monitor system uptime: uptime
🧯 If You Can't Patch
- Implement aggressive memory monitoring with alerts for abnormal slab growth
- Schedule regular system reboots to clear accumulated memory leaks
🔍 How to Verify
Check if Vulnerable:
Check if system uses bcm_sf2 driver: lsmod | grep bcm_sf2. Check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Monitor slab memory usage over time after applying patch: watch -n 60 'cat /proc/meminfo | grep Slab'📡 Detection & Monitoring
Log Indicators:
- Kernel oom-killer messages
- System instability logs
- High memory usage alerts
Network Indicators:
- Network interface instability
- Increased packet loss on affected interfaces
SIEM Query:
source="kernel" AND ("Out of memory" OR "slab" OR "oom")🔗 References
- https://git.kernel.org/stable/c/7feef10768ea71d468d9bbc1e0d14c461876768c
- https://git.kernel.org/stable/c/a7d2808d67570e6acae45c2a96e0d59986888e4c
- https://git.kernel.org/stable/c/b7b8d9f5e679af60c94251fd6728dde34be69a71
- https://git.kernel.org/stable/c/c05516c072903f6fb9134b8e7e1ad4bffcdc4819
- https://git.kernel.org/stable/c/e3862093ee93fcfbdadcb7957f5f8974fffa806a
- https://git.kernel.org/stable/c/f3d5efe18a11f94150fee8b3fda9d62079af640a
- https://lists.debian.org/debian-lts-announce/2024/10/msg00003.html
- https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html
