CVE-2022-49147: block: Fix the maximum minor value is blk_alloc_ext_minor()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-26 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: block: Fix the maximum minor value is blk_alloc_ext_minor() ida_alloc_range(..., min, max, ...) returns values from min to max, inclusive. So, NR_EXT_DEVT is a valid idx returned by blk_alloc_ext_minor(). This is an issue because in device_add_disk(), this value is used in: ddev->devt = MKDEV(disk->major, disk->first_minor); and NR_EXT_DEVT is '(1 << MINORBITS)'. So, should 'disk->first_minor' be NR_EXT_DEVT, it would overflow.

Affected products

Linux kernel: from 5.11 before 5.15.33; from 5.16 before 5.16.19; from 5.17 before 5.17.2 — fixed in 5.15.33, 5.16.19, 5.17.2

How to fix

Upgrade to a fixed version: Linux kernel 5.15.33, 5.16.19, 5.17.2. Check the vendor advisory for mitigations.

References

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