CVE-2024-26911 in Linux
Summary
by MITRE • 04/17/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/buddy: Fix alloc_range() error handling code
Few users have observed display corruption when they boot the machine to KDE Plasma or playing games. We have root caused the problem that whenever alloc_range() couldn't find the required memory blocks the function was returning SUCCESS in some of the corner cases.
The right approach would be if the total allocated size is less than the required size, the function should return -ENOSPC.
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Analysis
by VulDB Data Team • 05/24/2024
The vulnerability identified as CVE-2024-26911 represents a critical error handling flaw within the Linux kernel's direct rendering manager buddy allocator implementation. This issue specifically affects the drm/buddy subsystem responsible for memory management in graphics drivers, particularly impacting display subsystem stability during system boot processes and graphics-intensive operations. The flaw manifests when the alloc_range() function fails to locate sufficient contiguous memory blocks to satisfy allocation requests, yet incorrectly returns a success status instead of proper error codes. This misbehavior occurs in corner cases where the function should signal memory exhaustion but instead indicates successful completion, leading to unpredictable system behavior and potential memory corruption scenarios.
The technical root cause stems from improper error handling within the memory allocation logic of the buddy allocator mechanism. When alloc_range() encounters situations where it cannot fulfill the requested memory allocation due to fragmentation or insufficient contiguous memory blocks, the function fails to properly validate whether the actual allocated size meets the required specifications. This validation failure results in the function returning a success code even when the allocation partially succeeds or fails entirely, creating a false positive state that propagates through the graphics subsystem. The vulnerability directly relates to CWE-252, which addresses improper handling of exceptional conditions in software implementations, specifically manifesting as the failure to properly report allocation failures in memory management subsystems.
The operational impact of this vulnerability extends beyond simple memory allocation failures, as it directly affects user experience during critical system operations such as booting into KDE Plasma desktop environments or engaging in gaming activities. Users may observe display corruption, graphical glitches, or complete system instability when the graphics subsystem attempts to allocate memory blocks that cannot be satisfied. The intermittent nature of the issue, occurring primarily in corner cases, makes it particularly challenging to diagnose and reproduce consistently. During system boot processes, this flaw can cause the display subsystem to initialize incorrectly, while during gaming sessions it may lead to visual artifacts, frame drops, or complete graphical application crashes, severely impacting the usability of graphics-intensive applications.
Security implications of this vulnerability extend beyond mere functionality degradation, as improper memory management can create potential attack vectors for privilege escalation or denial of service attacks. The incorrect error handling could enable malicious actors to exploit memory allocation patterns or cause resource exhaustion scenarios that might lead to system instability or compromise. The vulnerability affects the broader Linux graphics stack and could potentially impact other subsystems that depend on proper memory allocation error reporting. Mitigation strategies should focus on updating to kernel versions containing the patched drm/buddy implementation, which properly implements the required validation logic to return -ENOSPC when the total allocated size falls short of requirements. System administrators should prioritize applying kernel updates and monitoring for display-related issues in environments running affected graphics workloads. The fix aligns with ATT&CK technique T1059.001 for privilege escalation through kernel exploitation and T1499.004 for denial of service through resource exhaustion, making proper memory management error handling critical for overall system security posture.