CVE-2025-39728
📋 TL;DR
This CVE describes an array bounds vulnerability in the Linux kernel's Samsung clock management unit driver. When UBSAN (Undefined Behavior Sanitizer) is enabled with array bounds checking, the system can panic due to accessing an array before proper initialization. This affects Linux systems using Samsung Exynos ARM64 processors with the vulnerable kernel driver.
💻 Affected Systems
- Linux kernel with Samsung clock management unit 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
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
System crash when UBSAN_ARRAY_BOUNDS=y is enabled during kernel compilation, resulting in denial of service.
If Mitigated
No impact if UBSAN array bounds checking is disabled or the system doesn't use the affected Samsung clock driver.
🎯 Exploit Status
Exploitation requires specific kernel configuration (UBSAN_ARRAY_BOUNDS=y) and hardware, making it unlikely to be weaponized for remote attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 00307934eb94aaa0a99addfb37b9fe206f945004, 0fef48f4a70e45a93e73c39023c3a6ea624714d6, 157de9e48007a20c65d02fc0229a16f38134a72d, 24307866e0ac0a5ddb462e766ceda5e27a6fbbe3, 4d29a6dcb51e346595a15b49693eeb728925ca43
Vendor Advisory: https://git.kernel.org/stable/c/00307934eb94aaa0a99addfb37b9fe206f945004
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Recompile kernel if using custom build. 3. Reboot system to load patched kernel.
🔧 Temporary Workarounds
Disable UBSAN array bounds checking
linuxCompile kernel without UBSAN_ARRAY_BOUNDS=y to avoid triggering the vulnerability
make menuconfig
Navigate to Kernel hacking -> Generic Kernel Debugging Instruments -> Undefined behavior sanity checker
Disable 'Enable array bounds checking'
🧯 If You Can't Patch
- Disable UBSAN array bounds checking in kernel configuration and recompile
- Avoid using affected Samsung Exynos ARM64 hardware if possible
🔍 How to Verify
Check if Vulnerable:
Check kernel version and configuration: 1. uname -r 2. Check if kernel was compiled with UBSAN_ARRAY_BOUNDS=y in /proc/config.gz or /boot/config-$(uname -r)Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits: grep -q 'samsung_clk_init' /proc/kallsyms && check kernel version against patched versions📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages containing 'UBSAN: array index out of bounds' and 'samsung_clk_init' in call trace
Network Indicators:
- None - this is a local kernel issue
SIEM Query:
event_type:"kernel_panic" AND message:"UBSAN: array index out of bounds" AND message:"samsung_clk_init"🔗 References
- https://git.kernel.org/stable/c/00307934eb94aaa0a99addfb37b9fe206f945004
- https://git.kernel.org/stable/c/0fef48f4a70e45a93e73c39023c3a6ea624714d6
- https://git.kernel.org/stable/c/157de9e48007a20c65d02fc0229a16f38134a72d
- https://git.kernel.org/stable/c/24307866e0ac0a5ddb462e766ceda5e27a6fbbe3
- https://git.kernel.org/stable/c/4d29a6dcb51e346595a15b49693eeb728925ca43
- https://git.kernel.org/stable/c/a1500b98cd81a32fdfb9bc63c33bb9f0c2a0a1bf
- https://git.kernel.org/stable/c/d19d7345a7bcdb083b65568a11b11adffe0687af
- https://git.kernel.org/stable/c/d974e177369c034984cece9d7d4fada9f8b9c740
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
