Executive Summary

CVE-2025-21817 exposes a deadlock risk in the Linux kernel when sysfs store callbacks run while the block queue is frozen. Memory allocations using GFP_KERNEL can trigger direct reclaim, potentially causing a deadlock. The patch marks these allocations with GFP_NOIO to prevent direct reclaim during the frozen state, restoring kernel stability.

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Authoritative CVE Metadata - CVSS Base Score: 5.5 (MEDIUM) - Published: 2025-02-27T20:16:04.243 - Last Modified: 2026-09-07T16:17:27.213

Original Description: In the Linux kernel, the following vulnerability has been resolved:

block: mark GFP_NOIO around sysfs ->store()

sysfs ->store is called with queue freezed, meantime we have several ->store() callbacks(update_nr_requests, wbt, scheduler) to allocate memory with GFP_KERNEL which may run into direct reclaim code path, then potential deadlock can be caused.

Fix the issue by marking NOIO around sysfs ->store()

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