CVE-2024-47704 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check link_res->hpo_dp_link_enc before using it
[WHAT & HOW]
Functions dp_enable_link_phy and dp_disable_link_phy can pass link_res without initializing hpo_dp_link_enc and it is necessary to check for null before dereferencing.
This fixes 2 FORWARD_NULL issues reported by Coverity.
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Analysis
by VulDB Data Team • 01/19/2026
The vulnerability identified as CVE-2024-47704 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 vulnerability that can occur during the handling of DisplayPort link management operations. The flaw manifests when functions responsible for enabling and disabling DisplayPort link physical layers fail to properly initialize critical data structures before utilization, creating a scenario where subsequent code attempts to dereference a null pointer reference.
The technical implementation of this vulnerability stems from the improper initialization of the hpo_dp_link_enc member within the link_res structure. When dp_enable_link_phy and dp_disable_link_phy functions are invoked, they may pass link_res parameters that contain uninitialized hpo_dp_link_enc fields. This initialization gap creates a dangerous condition where the driver code attempts to access memory locations through a null pointer, leading to potential system crashes or unauthorized code execution. The vulnerability was identified through static analysis tools and specifically flagged by Coverity as two FORWARD_NULL issues, indicating that the code follows a path where a pointer is used without proper validation of its null status.
The operational impact of this vulnerability extends beyond simple system instability, potentially enabling privilege escalation attacks within the kernel space. When a null pointer dereference occurs in kernel mode, it can result in system crashes that may be exploited to gain elevated privileges or cause denial of service conditions. The vulnerability affects systems running Linux kernels with AMD display drivers, particularly those utilizing DisplayPort connections for external displays. Attackers who can trigger the specific code path involving uninitialized link_res structures may be able to cause system panics or potentially exploit the memory corruption for more advanced attack vectors.
Mitigation strategies for CVE-2024-47704 focus on ensuring proper initialization of all data structures before use, with the primary fix involving the addition of null pointer checks before dereferencing hpo_dp_link_enc. System administrators should prioritize updating their Linux kernels to versions that include the patched drm/amd/display driver components. The fix implements defensive programming practices that align with common vulnerability prevention techniques described in CWE-476, which specifically addresses null pointer dereference issues. Additionally, the remediation approach follows ATT&CK framework techniques related to privilege escalation and defense evasion, as proper input validation and initialization help prevent exploitation of kernel-level vulnerabilities. Organizations should also consider implementing kernel hardening measures such as stack canaries and address space layout randomization to further reduce the attack surface and potential impact of similar vulnerabilities.