CVE-2026-43398 in Linux
Summary
by MITRE • 05/08/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: add upper bound check on user inputs in wait ioctl
Huge input values in amdgpu_userq_wait_ioctl can lead to a OOM and could be exploited.
So check these input value against AMDGPU_USERQ_MAX_HANDLES which is big enough value for genuine use cases and could potentially avoid OOM.
v2: squash in Srini's fix
(cherry picked from commit fcec012c664247531aed3e662f4280ff804d1476)
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability in question affects the Linux kernel's amdgpu driver component, specifically within the drm/amdgpu subsystem where the wait ioctl functionality processes user inputs. This issue arises from insufficient validation of input parameters in the amdgpu_userq_wait_ioctl function, creating a potential pathway for malicious exploitation through crafted input values that could trigger system resource exhaustion.
The technical flaw stems from the absence of proper upper bound validation on user-supplied parameters within the ioctl handler. When large input values are passed to the wait ioctl function, they can cause the kernel to attempt allocation of excessive memory resources, leading to out-of-memory conditions that may result in system instability or denial of service. This vulnerability represents a classic case of insufficient input validation that can be exploited to consume system resources beyond normal operational limits.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it could potentially enable attackers to perform denial of service attacks against systems running amdgpu drivers. The exploitability of this condition is particularly concerning given that it operates at the kernel level where malicious input can directly affect system stability and availability. The vulnerability affects systems utilizing AMD GPU hardware through the amdgpu driver and could be leveraged by attackers to disrupt normal system operations.
The fix implemented addresses this issue by introducing a boundary check against the AMDGPU_USERQ_MAX_HANDLES constant, which serves as a reasonable upper limit for legitimate user operations while preventing excessive resource consumption. This approach aligns with established security principles of input validation and resource limitation that are fundamental to preventing resource exhaustion attacks. The solution represents a defensive programming technique that ensures user inputs remain within acceptable operational parameters.
This vulnerability demonstrates the importance of proper input validation in kernel space operations, particularly within device driver code where user-supplied data can directly influence system resource management. The fix follows security best practices by implementing explicit bounds checking and establishing reasonable limits for user inputs. From an industry standards perspective, this addresses CWE-129 which covers insufficient input validation and relates to ATT&CK technique T1499.004 for resource exhaustion attacks. The solution represents a straightforward but critical defensive measure that prevents malicious exploitation while maintaining functionality for legitimate use cases, ensuring that the amdgpu driver operates within safe memory allocation parameters.