CVE-2025-71124 Overview
CVE-2025-71124 is a NULL pointer dereference vulnerability in the Linux kernel's DRM (Direct Rendering Manager) subsystem, specifically affecting the MSM (Qualcomm Mobile Station Modem) A6XX GPU driver. The vulnerability exists in the GPU preemption handling code where the preempt_prepare_postamble() function is called before verifying that preempt_postamble_ptr is valid.
If preempt_postamble_ptr is NULL due to a failed postamble allocation, dereferencing it in preempt_prepare_postamble() leads to a kernel crash. This vulnerability affects systems using Qualcomm Adreno A6XX series GPUs with the MSM DRM driver.
Critical Impact
Exploitation of this vulnerability can cause kernel crashes and system denial of service on affected Linux systems with Qualcomm Adreno A6XX GPUs.
Affected Products
- Linux kernel with DRM MSM A6XX driver enabled
- Systems with Qualcomm Adreno A6XX series GPUs
- Mobile devices and embedded systems using MSM DRM subsystem
Discovery Timeline
- 2026-01-14 - CVE-2025-71124 published to NVD
- 2026-01-14 - Last updated in NVD database
Technical Details for CVE-2025-71124
Vulnerability Analysis
The vulnerability stems from improper error handling in the A6XX GPU preemption code path. The DRM MSM driver implements GPU preemption to allow context switching between GPU workloads. During the preparation phase, a postamble buffer is allocated to store GPU state information required for preemption operations.
The root issue is that the preempt_prepare_postamble() function was being invoked before the code verified whether the preempt_postamble_ptr allocation succeeded. When the postamble memory allocation fails, the pointer remains NULL, and subsequent access to this pointer within the preparation function triggers a NULL pointer dereference, causing an immediate kernel panic.
This vulnerability is classified as a Null Pointer Dereference issue that can result in denial of service conditions on affected systems.
Root Cause
The root cause is a missing error check in the code flow. The preempt_prepare_postamble() function call was positioned before the validation logic that checks whether preempt_postamble_ptr contains a valid memory address. Proper defensive programming requires validating pointer allocations before any operations that would dereference them.
The fix involves reordering the function calls so that preempt_prepare_postamble() is only invoked after confirming that preempt_postamble_ptr is not NULL, ensuring proper error handling when memory allocation fails.
Attack Vector
The vulnerability can be triggered when the kernel's memory allocation for the preemption postamble fails due to memory pressure or resource exhaustion. While this may occur naturally under high system load, an attacker with local access could potentially engineer conditions that cause memory allocation failures, leading to repeated kernel crashes and system instability.
The attack requires local access to the system and the ability to interact with the GPU subsystem, either through graphics operations or direct DRM interface access.
Detection Methods for CVE-2025-71124
Indicators of Compromise
- Kernel panic messages referencing preempt_prepare_postamble or related A6XX driver functions
- System crashes during GPU-intensive operations on Qualcomm Adreno A6XX hardware
- Repeated NULL pointer dereference errors in kernel logs related to the DRM MSM subsystem
Detection Strategies
- Monitor kernel logs (dmesg) for NULL pointer dereference exceptions in the drm/msm/a6xx module
- Configure kernel crash dump analysis to identify crashes originating from the A6XX preemption code path
- Implement system monitoring for unexpected kernel panics on systems with Qualcomm GPUs
Monitoring Recommendations
- Enable kernel crash reporting and analysis tools such as kdump or crash
- Set up automated alerting for kernel oops messages containing DRM MSM driver references
- Monitor system stability metrics on devices running affected kernel versions with A6XX GPUs
How to Mitigate CVE-2025-71124
Immediate Actions Required
- Update the Linux kernel to a patched version that includes the fix for CVE-2025-71124
- Review kernel version and DRM MSM driver configuration on systems with Qualcomm Adreno A6XX GPUs
- Monitor systems for stability issues while awaiting patch deployment
Patch Information
The Linux kernel maintainers have released patches to address this vulnerability. The fix moves the preempt_prepare_postamble() call after the error check that validates preempt_postamble_ptr is not NULL.
Patches are available through the following kernel commits:
Additional patch details are available via the Patchwork submission.
Workarounds
- If immediate patching is not possible, consider disabling GPU preemption features if supported by your kernel configuration
- Limit access to GPU-related system calls on multi-user systems to reduce attack surface
- Ensure adequate system memory to reduce likelihood of allocation failures triggering the vulnerability
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
