Bug 2425209 (CVE-2022-50756)

Summary:	CVE-2022-50756 kernel: nvme-pci: fix mempool alloc size
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was addressed in the Linux kernel’s nvme-pci driver related to how the driver calculated the worst-case number of PRP (Physical Region Page) lists required for a given I/O request. The implementation previously rounded the allocation to one list instead of correctly converting the maximum size into bytes before computing the divisor. Under certain rare conditions (for example, a 4 MiB transfer split across many physical segments on a queue that does not support SGLs), this calculation error could result in memory being corrupted beyond the size provided by the mempool. This memory corruption has been observed using kfence	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2025-12-24 14:10:58 UTC

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.

Comment 1 Alexander B 2025-12-24 18:31:59 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122453-CVE-2022-50756-ce43@gregkh/T