CVE intelligence and bounded remediation

CVE-2026-31656 — Linux Linux Kernel security vulnerability

High CVSS 7.8

In the Linux kernel, the following vulnerability has been resolved: drm/i915/gt: fix refcount underflow in intel_engine_park_heartbeat A use-after-free / refcount underflow is possible when the heartbeat worker and intel_engine_park_heartbeat() race to release the same engine->heartbeat.systole request. The heartbeat worker reads engine->heartbeat.systole and calls i915_request_put() on it when the request is complete, but clears the pointer in a separate, non-atomic step. Concurrently, a request retirement on another CPU can drop the engine wakeref to zero, triggering __engine_park() -> intel_engine_park_heartbeat(). If the heartbeat timer is pending at that point, cancel_delayed_work() returns true and intel_engine_park_heartbeat() reads the stale non-NULL systole pointer and calls i915_request_put() on it again, causing a refcount underflow: ``` <4> [487.221889] Workqueue: i915-unordered engine_retire [i915] <4> [487.222640] RIP: 0010:refcount_warn_saturate+0x68/0xb0 ... <4> [487.222707] Call Trace: <4> [487.222711] <TASK> <4> [487.222716] intel_engine_park_heartbeat.part.0+0x6f/0x80 [i915] <4> [487.223115] intel_engine_park_heartbeat+0x25/0x40 [i915] <4> [487.223566] __engine_…

Severity
High
CVSS
7.8 (3.1)
Published
2026-04-24
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-191

Affected products

  • linux / linux_kernel
  • linux / linux_kernel / 5.5
  • linux / linux_kernel / 7.0

Showing 3 representative product identities from 14 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Use-after-free, double free, and expired resource use

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace ownership, references, callbacks, asynchronous tasks, and teardown paths around the affected object or resource.
  • Identify reachable inputs and timing or state transitions that can release the object while references remain.
  • Confirm affected builds, allocators, feature flags, architectures, and process privileges.

Remediate safely

  • Apply the maintained ownership or lifetime fix and rebuild all artifacts containing the affected native code.
  • Use explicit ownership, safe reference management, cancellation and join semantics, and idempotent teardown.
  • Add deterministic lifetime tests plus isolated sanitizer and concurrency coverage for shutdown and error paths.

Authoritative sources

Complete CVE record and remediation plan

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