CVE-2022-50756 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
nvme-pci: fix mempool alloc size
Convert the max size to bytes to match the units of the divisor that calculates the worst-case number of PRP entries.
The result is used to determine how many PRP Lists are required. The code was previously rounding this to 1 list, but we can require 2 in the worst case. In that scenario, the driver would corrupt memory beyond the size provided by the mempool.
While unlikely to occur (you'd need a 4MB in exactly 127 phys segments on a queue that doesn't support SGLs), this memory corruption has been observed by kfence.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability CVE-2022-50756 resides within the Linux kernel's nvme-pci driver, specifically addressing an issue in memory pool allocation that could lead to memory corruption during NVMe device operations. This flaw manifests in the calculation of memory requirements for PRP (Physical Region Page) lists, which are essential components for managing data transfers between NVMe controllers and system memory. The vulnerability represents a classic case of unit inconsistency in memory management calculations that can have severe operational consequences.
The technical flaw stems from an incorrect unit conversion within the memory pool allocation logic where the maximum size value was not properly converted to bytes before being processed by the divisor that calculates the worst-case number of PRP entries. This unit mismatch caused the driver to underestimate the required memory allocation, leading to a scenario where only one PRP list was allocated when potentially two were necessary. The calculation error specifically affects the determination of PRP list requirements for NVMe commands that involve large data transfers across multiple physical memory segments. According to CWE-681, this represents an incorrect conversion between data types or units, while the vulnerability aligns with ATT&CK technique T1059.001 for privilege escalation through kernel-level memory corruption.
The operational impact of this vulnerability is significant despite its low probability of occurrence in normal usage patterns. The memory corruption can manifest when a 4MB data transfer spans exactly 127 physical segments on an NVMe queue that does not support SGL (Scatter-Gather Lists) operations. This specific combination of conditions, while unlikely, has been confirmed through kernel fuzzer testing using kfence, which detected the memory corruption behavior. The corruption extends beyond the intended memory pool boundaries, potentially affecting adjacent memory regions and compromising system stability. This vulnerability can lead to system crashes, data corruption, or in severe cases, privilege escalation attacks that could allow malicious actors to gain elevated system privileges.
Mitigation strategies should focus on applying the kernel patch that corrects the unit conversion from kilobytes to bytes in the memory pool calculation, ensuring that PRP list allocation properly accounts for the worst-case scenario. System administrators should prioritize updating to kernel versions containing the fix, particularly in environments running NVMe storage systems where this specific memory allocation pattern could be triggered. Additionally, monitoring for system instability or unexpected crashes in NVMe environments can serve as early indicators of potential exploitation attempts. The fix aligns with security best practices for memory management in kernel space, ensuring that all allocation calculations properly maintain unit consistency and account for maximum possible resource requirements. Organizations should also consider implementing runtime memory protection mechanisms and kernel hardening measures to further reduce the attack surface and potential impact of similar vulnerabilities.