CVE-2025-39693 in Linux
Summary
by MITRE • 09/05/2025
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Avoid a NULL pointer dereference
[WHY]
Although unlikely drm_atomic_get_new_connector_state() or drm_atomic_get_old_connector_state() can return NULL.
[HOW]
Check returns before dereference.
(cherry picked from commit 1e5e8d672fec9f2ab352be121be971877bff2af9)
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Analysis
by VulDB Data Team • 02/09/2026
The vulnerability identified as CVE-2025-39693 resides within the Linux kernel's display subsystem, specifically affecting the AMD display driver component known as drm/amd/display. This issue represents a classic null pointer dereference condition that could potentially lead to system instability or denial of service. The vulnerability manifests in the atomic display state management functions where the kernel attempts to access connector state information without proper validation of the returned pointer values. The underlying problem occurs when the drm_atomic_get_new_connector_state() or drm_atomic_get_old_connector_state() functions return NULL pointers, which then get dereferenced without prior validation checks.
The technical flaw stems from inadequate input validation within the display management code path. When the kernel processes atomic display state updates, it calls these state retrieval functions to obtain current and previous connector states. However, the code does not properly verify whether these functions successfully returned valid pointer references before proceeding with operations that require dereferencing. This pattern creates a potential execution path where a NULL pointer is accessed, leading to a kernel panic or system crash. The vulnerability is categorized under CWE-476 as a NULL pointer dereference, which represents a fundamental programming error that violates secure coding practices and can be exploited to disrupt system operations.
The operational impact of this vulnerability extends beyond simple system crashes, as it can affect the stability of graphics-intensive applications and desktop environments. When triggered, the null pointer dereference causes the kernel to terminate the current execution context, potentially resulting in complete system lockup or reboot. This disruption is particularly concerning in server environments where continuous operation is critical, or in embedded systems where display functionality is essential for user interaction. The vulnerability affects systems running Linux kernels with AMD graphics drivers, particularly those implementing atomic modesetting functionality for display management. The attack surface is relatively narrow since it requires specific conditions to trigger the problematic code path, but the consequences can be severe for affected systems.
Mitigation strategies for CVE-2025-39693 focus on implementing proper input validation and defensive programming practices. The fix involves adding explicit NULL pointer checks before dereferencing the return values from the atomic state retrieval functions. This approach aligns with the principle of least privilege and defensive programming, ensuring that all pointer operations include validation before execution. System administrators should prioritize applying the kernel patch that includes the cherry-picked commit 1e5e8d672fec9f2ab352be121be971877bff2af9, which implements the required validation checks. The solution follows ATT&CK technique T1059.001 for command and scripting interpreter, as it involves modifying kernel-level code to prevent unauthorized access patterns. Organizations should also consider implementing monitoring solutions to detect potential exploitation attempts and maintain regular kernel updates to address similar vulnerabilities in the display subsystem. The fix demonstrates proper error handling mechanisms that prevent privilege escalation through memory corruption attacks and aligns with industry best practices for kernel security hardening.