CVE-2024-46776 in Linux
Summary
by MITRE • 09/18/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Run DC_LOG_DC after checking link->link_enc
[WHAT]
The DC_LOG_DC should be run after link->link_enc is checked, not before.
This fixes 1 REVERSE_INULL issue reported by Coverity.
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Analysis
by VulDB Data Team • 04/06/2026
The vulnerability identified as CVE-2024-46776 resides within the Linux kernel's display subsystem, specifically within the drm/amd/display driver component. This issue represents a subtle but significant flaw in the logical execution order of code paths that handle display link encoding operations. The problem manifests in the improper sequencing of operations where debugging log output occurs before critical null pointer validation checks. The vulnerability was detected and resolved through Coverity static analysis tooling, which identified a reverse null pointer dereference condition that could potentially lead to system instability or information disclosure.
The technical flaw stems from a violation of proper defensive programming practices where the DC_LOG_DC macro execution precedes the necessary validation of the link->link_enc pointer. This ordering issue creates a scenario where debug logging operations may attempt to access memory locations that have not yet been validated for nullity, potentially leading to undefined behavior. The vulnerability specifically addresses a REVERSE_INULL issue, which indicates that the code path checks for a null pointer in the wrong sequence, allowing for potential null pointer dereference conditions that could be exploited or at minimum cause system crashes.
The operational impact of this vulnerability extends beyond simple system stability concerns into potential security implications for systems running affected Linux kernel versions. When the display subsystem processes link encoding operations, particularly in scenarios involving AMD graphics hardware, the improper execution order could lead to kernel oops, system crashes, or in worst-case scenarios, potential information leakage through memory access patterns. This issue affects systems utilizing AMD display controllers and could be particularly problematic in server or embedded environments where display functionality is critical or where systems may be under attack from malicious actors seeking to exploit kernel vulnerabilities.
The resolution implemented addresses the core issue by reordering the code execution to ensure that the link->link_enc pointer validation occurs before any debugging log operations are performed. This change aligns with established security best practices and defensive programming principles that emphasize validating all pointer references before dereferencing them. The fix directly addresses the CWE-476 principle of null pointer dereference by ensuring proper validation order. From an ATT&CK perspective, this vulnerability would be classified under technique T1068 for locally exploited privilege escalation opportunities, though the primary risk remains system stability rather than direct privilege compromise. Organizations should prioritize applying this patch to all systems running affected kernel versions to prevent potential exploitation scenarios and maintain system reliability in display-related operations.