CVE-2026-31656

Katalog CVE

CVSS 7.8 · High EPSS 0,17%

Kerentanan Integer Underflow (Wrap or Wraparound) pada linux kernel. Skor CVSS 3.1 7.8 (High) menurut CNA.

Deskripsi (NVD)

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_park+0xb9/0x650 [i915] <4> [487.223973] ____intel_wakeref_put_last+0x2e/0xb0 [i915] <4> [487.224408] __intel_wakeref_put_last+0x72/0x90 [i915] <4> [487.224797] intel_context_exit_engine+0x7c/0x80 [i915] <4> [487.225238] intel_context_exit+0xf1/0x1b0 [i915] <4> [487.225695] i915_request_retire.part.0+0x1b9/0x530 [i915] <4> [487.226178] i915_request_retire+0x1c/0x40 [i915] <4> [487.226625] engine_retire+0x122/0x180 [i915] <4> [487.227037] process_one_work+0x239/0x760 <4> [487.227060] worker_thread+0x200/0x3f0 <4> [487.227068] ? __pfx_worker_thread+0x10/0x10 <4> [487.227075] kthread+0x10d/0x150 <4> [487.227083] ? __pfx_kthread+0x10/0x10 <4> [487.227092] ret_from_fork+0x3d4/0x480 <4> [487.227099] ? __pfx_kthread+0x10/0x10 <4> [487.227107] ret_from_fork_asm+0x1a/0x30 <4> [487.227141] </TASK> ``` Fix this by replacing the non-atomic pointer read + separate clear with xchg() in both racing paths. xchg() is a single indivisible hardware instruction that atomically reads the old pointer and writes NULL. This guarantees only one of the two concurrent callers obtains the non-NULL pointer and performs the put, the other gets NULL and skips it. (cherry picked from commit 13238dc0ee4f9ab8dafa2cca7295736191ae2f42)

Rincian

Terbit di NVD

24 April 2026

Terakhir diubah

17 Juni 2026

Status NVD

Modified

CVSS 3.1

7.8 (High), sumber CNA
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H · uraikan di kalkulator

Jenis kelemahan (CWE)

CWE-191: Integer Underflow (Wrap or Wraparound)

EPSS (30 hari)

0,17% peluang dieksploitasi; lebih tinggi dari 5,9% CVE lain

Produk dan versi terdampak

> Data dari konfigurasi CPE di NVD.

Referensi dan perbaikan

• https://git.kernel.org/stable/c/2af8b200cae3fdd0e917ecc2753b28bb40c876c1 patch
• https://git.kernel.org/stable/c/455d98ed527fc94eed90406f90ab2391464ca657 patch
• https://git.kernel.org/stable/c/4c71fd099513bfa8acab529b626e1f0097b76061 patch
• https://git.kernel.org/stable/c/70d3e622b10092fc483e28e57b4e8c49d9cc7f68 patch
• https://git.kernel.org/stable/c/8ce44d28a84fd5e053a88b04872a89d95c0779d4 patch
• https://git.kernel.org/stable/c/a00e92bf6583d019a4fb2c2df7007e6c9b269ce7 patch
• https://git.kernel.org/stable/c/ca3f48c3567dd49efdc55b80029ae74659c682ee patch
• https://git.kernel.org/stable/c/82034799c6c14b3104668878c3f3e5786f777126