CVE-2024-43904 in Linux
Summary
by MITRE • 08/26/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Add null checks for 'stream' and 'plane' before dereferencing
This commit adds null checks for the 'stream' and 'plane' variables in the dcn30_apply_idle_power_optimizations function. These variables were previously assumed to be null at line 922, but they were used later in the code without checking if they were null. This could potentially lead to a null pointer dereference, which would cause a crash.
The null checks ensure that 'stream' and 'plane' are not null before they are used, preventing potential crashes.
Fixes the below static smatch checker: drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:938 dcn30_apply_idle_power_optimizations() error: we previously assumed 'stream' could be null (see line 922) drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:940 dcn30_apply_idle_power_optimizations() error: we previously assumed 'plane' could be null (see line 922)
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Analysis
by VulDB Data Team • 09/28/2024
The vulnerability identified as CVE-2024-43904 represents a critical null pointer dereference flaw within the Linux kernel's AMD display driver subsystem, specifically affecting the dcn30_apply_idle_power_optimizations function. This issue resides in the display controller hardware sequence implementation for AMD graphics hardware, where the code previously made assumptions about variable initialization without proper validation. The flaw occurs in the drm/amd/display component of the kernel's graphics stack, which manages display output for AMD GPUs and is integral to system stability when handling power optimization routines.
The technical implementation of this vulnerability stems from inadequate null pointer validation in the dcn30_hwseq.c source file at lines 938 and 940. The static analysis tool smatch identified that variables 'stream' and 'plane' were initially assumed to be null at line 922 but were subsequently dereferenced without proper null checks. This pattern violates fundamental secure coding practices and creates a condition where the kernel could attempt to access memory locations that do not contain valid data structures. The vulnerability is classified as a null pointer dereference, which directly maps to CWE-476 in the Common Weakness Enumeration catalog, specifically addressing the absence of null checks for pointers that may legitimately be null.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential denial of service condition that could affect graphics rendering and display functionality on systems utilizing AMD GPUs. When the kernel encounters this null pointer dereference during idle power optimization routines, the system may experience unexpected termination of display services, leading to complete loss of graphical output or system instability. This affects any system running the affected Linux kernel version with AMD graphics hardware, potentially impacting desktop environments, server workloads, and embedded systems that rely on AMD GPU display capabilities. The vulnerability is particularly concerning because it occurs during power management operations, which are frequent and critical system functions that could trigger the flaw under normal operating conditions.
Mitigation strategies for this vulnerability involve applying the kernel patch that introduces null checks for both 'stream' and 'plane' variables before any dereferencing operations occur. System administrators should prioritize updating to kernel versions containing the fix, typically those incorporating the commit that addresses this specific issue. Organizations managing AMD GPU environments should implement comprehensive patch management procedures to ensure all systems receive the security update promptly. The fix aligns with ATT&CK technique T1499.004 for system disruption, as it prevents unauthorized denial of service conditions that could be exploited by malicious actors to destabilize systems. Additionally, this vulnerability highlights the importance of static analysis tools in identifying potential null pointer issues, as the smatch checker was instrumental in detecting this flaw before it could be exploited in production environments.