CVE-2024-49921 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Check null pointers before used
[WHAT & HOW]
Poniters, such as dc->clk_mgr, are null checked previously in the same function, so Coverity warns "implies that "dc->clk_mgr" might be null". As a result, these pointers need to be checked when used again.
This fixes 10 FORWARD_NULL issues reported by Coverity.
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Analysis
by VulDB Data Team • 03/04/2026
The vulnerability identified as CVE-2024-49921 represents a critical null pointer dereference issue within the Linux kernel's AMD display driver subsystem. This flaw exists in the drm/amd/display component where the kernel fails to properly validate pointer references before utilization, creating potential system instability and security risks. The issue manifests when the code attempts to access dc->clk_mgr and other similar pointers without proper null checking, despite previous null checks having been performed within the same function. This pattern creates a false positive in static analysis tools like Coverity, which incorrectly identifies these scenarios as potential null pointer dereferences. The vulnerability specifically affects the display management functionality of AMD graphics hardware within the Linux kernel ecosystem, potentially leading to system crashes or denial of service conditions when display operations are performed.
The technical implementation flaw stems from improper pointer validation logic within the display driver code where developers assume that previously validated null checks will persist throughout the function execution. This assumption proves incorrect when the code path involves multiple operations or when the null check occurs in a different scope than the subsequent pointer usage. The Coverity static analysis tool identifies 10 distinct FORWARD_NULL issues, indicating that the same pattern occurs across multiple locations within the drm/amd/display subsystem. These issues occur when the kernel attempts to access hardware clock management structures without ensuring they remain valid, creating opportunities for system crashes when the display subsystem processes graphics operations. The vulnerability demonstrates a classic software engineering error where defensive programming practices are insufficiently applied, particularly in complex kernel drivers where resource management becomes critical.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more sophisticated attack vectors. When a null pointer dereference occurs in kernel space, it can lead to privilege escalation opportunities or system compromise, particularly when combined with other vulnerabilities within the graphics subsystem. Attackers could exploit this weakness to cause denial of service against display functionality, potentially rendering systems unusable for graphics operations while maintaining system stability. The vulnerability affects all Linux systems utilizing AMD graphics hardware with the affected kernel version, making it a widespread concern for enterprise and consumer deployments. Organizations running display-intensive applications or systems requiring reliable graphics processing face heightened risk, as even a single null pointer dereference can cause cascading failures in graphics subsystems.
Mitigation strategies for CVE-2024-49921 should prioritize immediate kernel updates from vendors providing security patches for the drm/amd/display subsystem. System administrators should implement comprehensive monitoring for display-related system crashes or unexpected reboots that may indicate exploitation attempts. The fix implemented by the Linux kernel developers involves adding explicit null pointer checks before accessing dc->clk_mgr and similar pointers, addressing the root cause rather than merely suppressing false positives in static analysis. This remediation follows established security best practices and aligns with CWE-476, which addresses null pointer dereference vulnerabilities in software systems. Organizations should also consider implementing additional defensive measures such as kernel module hardening, privilege separation for graphics operations, and regular security scanning of kernel components to identify similar patterns. The vulnerability demonstrates the importance of continuous code review and static analysis integration within kernel development processes, particularly for critical subsystems like display drivers that handle hardware resource management.