CVE-2026-74454 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/vc4: Supply the overflow slot size in BPOS, not the whole bin BO size
vc4_overflow_mem_work() points BPOA at a 512KB slot inside the 16MB binner BO, but writes the size of the whole BO to BPOS. On every binner out-of-memory event the PTB is therefore authorized to write tile lists across all the other slots (which may hold the tile state, tile alloc and overflow memory of in-flight jobs) and, for any slot but the first, past the end of the binner BO into unrelated CMA memory.
Since CMA pages are recycled into page cache and user allocations, this is arbitrary memory corruption by GPU DMA. In practice it shows up as GPU hangs with corrupted control list pointers, userspace heap corruption, a GPU that stays permanently wedged after the first hang, and occasional full system crashes, whenever a job overflows the initial binner slot.
The bug dates back to the conversion from a dedicated overflow BO (where writing the full BO size was correct) to the slotted binner BO.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability resides within the drm/vc4 driver of the Linux kernel, specifically in how it handles memory management for GPU binner operations. This issue stems from an incorrect calculation of memory slot sizes during GPU memory allocation processes. The root cause occurs when the vc4_overflow_mem_work() function configures the BPOA register to point to a 512KB overflow slot within a larger 16MB binner BO, yet erroneously writes the complete BO size to the BPOS register instead of just the slot size. This fundamental mismatch creates a critical memory boundary violation that allows unauthorized memory access patterns.
The technical flaw manifests as a buffer overflow condition where the GPU's PTB (Programmable Tile Buffer) component receives incorrect size information for memory allocation boundaries. When out-of-memory conditions occur during binner operations, the system permits the PTB to write tile list data beyond the intended 512KB overflow slot boundaries. This allows writes to extend past the end of the designated binner BO and into adjacent memory regions containing critical data from other in-flight GPU jobs. The vulnerability specifically affects memory management within the CMA (Contiguous Memory Allocator) subsystem where pages are recycled between page cache and user allocations.
The operational impact of this vulnerability is severe and manifests through multiple failure modes that compromise system stability and data integrity. GPU hangs become frequent occurrences with corrupted control list pointers, while userspace heap corruption emerges as a secondary consequence of the arbitrary memory writes. The most critical aspect occurs when the GPU becomes permanently wedged after the first hang, rendering the graphics subsystem unusable until complete system reboot. System crashes may also occur during job overflow conditions, particularly when the corrupted memory regions contain critical kernel data structures or user-space allocations that are subsequently accessed.
This vulnerability aligns with CWE-121 stack-based buffer overflow and CWE-125 out-of-bounds read/write patterns, representing a classic case of improper boundary checking in memory management operations. The ATT&CK framework categorizes this under T1059 command and scripting interpreter for execution, as the memory corruption can lead to arbitrary code execution through kernel memory manipulation. The issue specifically relates to privilege escalation and system compromise through GPU DMA operations that bypass normal user-space protections.
Mitigation strategies should focus on correcting the memory size calculation within the vc4_overflow_mem_work() function to ensure BPOS register receives the correct slot size rather than the full BO size. The fix requires modifying the driver code to properly distinguish between the individual slot boundaries and the complete memory allocation when configuring GPU memory access parameters. Additionally, implementing proper bounds checking and memory validation mechanisms within the binner memory management subsystem will prevent similar issues from arising in future modifications. System administrators should ensure kernel updates are applied promptly to address this vulnerability, particularly in environments where GPU-intensive applications are deployed.