CVE-2026-63881 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: fix a vulnerability of integer overflow in kfd debugger
get_queue_ids() computes array_size = num_queues * sizeof(uint32_t), which could overflow on 32-bit size_t build. using array_size() instead, it saturates to SIZE_MAX on overflow.
(cherry picked from commit 2d57a0475f085c08b49312dfd8edcb461845f285)
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability resides within the AMD Kernel Driver Framework component of the Linux kernel, specifically addressing an integer overflow condition in the debugger functionality. The issue manifests in the get_queue_ids() function where the calculation array_size = num_queues * sizeof(uint32_t) fails to properly handle potential overflow scenarios on 32-bit systems where size_t is limited to 32 bits. This type of vulnerability falls under CWE-190, which classifies integer overflow conditions that can lead to unexpected behavior and potential exploitation. The flaw occurs when the multiplication of num_queues and sizeof(uint32_t) exceeds the maximum representable value for size_t on 32-bit architectures, creating a scenario where the computed array_size becomes smaller than expected due to wraparound behavior.
The operational impact of this vulnerability extends beyond simple memory allocation issues, as it represents a potential pathway for privilege escalation or denial of service attacks within kernel space. When an integer overflow occurs in memory allocation calculations, attackers could potentially manipulate the num_queues parameter to cause the system to allocate insufficient memory or trigger unexpected behavior during debugger operations. This vulnerability specifically affects systems running 32-bit Linux kernels where the size_t type cannot accommodate large values that might be legitimately requested by the kfd (Kernel Fire and Forget) debugger subsystem. The fix implemented addresses this by replacing the direct multiplication with array_size() function that implements saturation behavior, ensuring that overflow conditions result in SIZE_MAX rather than wrapping around to invalid values.
The remediation approach taken in this fix demonstrates adherence to secure coding practices recommended by both CWE guidelines and industry security standards. By implementing saturation behavior instead of allowing wraparound arithmetic, the kernel properly handles edge cases where large inputs might cause integer overflows. This solution aligns with ATT&CK technique T1068 which involves exploiting local system vulnerabilities, and specifically addresses the vulnerability through proper input validation and overflow handling mechanisms. The cherry-pick from commit 2d57a0475f085c08b49312dfd8edcb461845f285 indicates this is a well-tested and validated fix that has been integrated into the mainline kernel development cycle. This type of vulnerability is particularly concerning in kernel space contexts where memory corruption can lead to complete system compromise, making proper integer overflow handling essential for maintaining system integrity and security. The fix ensures that even when malicious or malformed input attempts to trigger this condition, the kernel will gracefully handle it by saturating to maximum values rather than allowing exploitable overflow behavior.
The broader implications of this vulnerability highlight the importance of thorough testing on all supported architectures, particularly 32-bit systems where integer overflow conditions are more likely to occur due to limited bit-width constraints. Modern kernel development practices emphasize the need for comprehensive input validation and overflow protection mechanisms, especially in components that interact with user-space applications through debugging interfaces. This vulnerability serves as a reminder of how seemingly simple arithmetic operations can become security-critical when operating in kernel space contexts where improper handling can lead to privilege escalation or system instability.