CVE-2022-50736 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
RDMA/siw: Fix immediate work request flush to completion queue
Correctly set send queue element opcode during immediate work request flushing in post sendqueue operation, if the QP is in ERROR state. An undefined ocode value results in out-of-bounds access to an array for mapping the opcode between siw internal and RDMA core representation in work completion generation. It resulted in a KASAN BUG report of type 'global-out-of-bounds' during NFSoRDMA testing.
This patch further fixes a potential case of a malicious user which may write undefined values for completion queue elements status or opcode, if the CQ is memory mapped to user land. It avoids the same out-of-bounds access to arrays for status and opcode mapping as described above.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-2022-50736 resides within the Linux kernel's RDMA software implementation known as siw (Software iWarp). This issue specifically affects the handling of immediate work requests during the post sendqueue operation when the queue pair transitions into an error state. The core problem manifests when the send queue element opcode is not correctly set during the flushing process, leading to the use of undefined opcode values that subsequently trigger out-of-bounds memory access patterns.
The technical flaw stems from improper handling of opcode mapping between siw's internal representation and the RDMA core's expected format during work completion generation. When a queue pair enters an error state, the system attempts to flush immediate work requests, but the opcode field remains uninitialized or improperly set. This creates a scenario where the kernel's completion queue processing logic accesses arrays using invalid indices derived from these undefined opcode values, resulting in a global-out-of-bounds memory access that triggers a KASAN (Kernel Address Sanitizer) BUG report. The vulnerability was particularly evident during NFSoRDMA testing scenarios where the RDMA subsystem is under stress from network file system operations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential attack vectors for malicious users who might exploit the memory mapping capabilities of completion queues. When a completion queue is memory mapped to user space, attackers can potentially manipulate the status or opcode fields of completion queue elements, leading to predictable out-of-bounds access patterns in kernel memory. This represents a significant security risk as it could allow privilege escalation or denial of service attacks, particularly in environments where RDMA is actively used for high-performance networking. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and demonstrates characteristics consistent with ATT&CK technique T1068, involving exploitation of system privileges.
The patch addressing CVE-2022-50736 specifically corrects the opcode setting behavior during immediate work request flushing operations when queue pairs are in error states. This ensures that the send queue element opcodes are properly initialized before being processed by the completion generation logic. The fix prevents the use of undefined values that would otherwise cause array index calculations to exceed valid bounds, thereby eliminating the global-out-of-bounds access patterns that triggered the KASAN BUG reports. Additionally, the patch strengthens the validation mechanisms for completion queue elements when they are memory mapped to user space, preventing malicious users from writing undefined values that could compromise system stability or security. This remediation directly addresses the kernel's memory safety requirements and aligns with security best practices for kernel-level buffer management and validation. The fix ensures that all opcode and status fields maintain valid values throughout the completion queue processing lifecycle, preventing both accidental corruption and malicious exploitation scenarios.