--- cve: "CVE-2026-64586" severity: "HIGH" cvss: 8.8 epss: "0.2%" vendor: "Linux" kev: false exploited: false published: "2026-08-06 07:06:27" tags: [cve, security, high] source: tsecurity.de CVE-Dossier exported: "2026-09-21T10:48:52+02:00" --- # CVE-2026-64586 > 8.8 HIGH ## Beschreibung In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: drain bus_reset work on device removal brcmf_fw_crashed() and the debugfs "reset" entry both schedule drvr->bus_reset, whose callback recovers drvr through container_of() and dereferences it. The removal path frees drvr (brcmf_free -> wiphy_free) without draining the work, so a bus_reset callback pending or running during removal can outlive drvr. Cancellation cannot live in brcmf_detach() or brcmf_free(): the work callback reaches teardown through the bus .reset op (PCIe brcmf_pcie_reset -> brcmf_detach; SDIO brcmf_sdio_bus_reset -> brcmf_sdiod_remove -> brcmf_free), so cancelling there would wait for the running work and deadlock. Add a per-bus mutex (bus_reset_lock) and route all arming through brcmf_bus_schedule_reset(), which under the lock skips when the bus is marked removing. Each bus remove entry calls brcmf_bus_cancel_reset_work(), which under the same lock sets removing and cancels the work. Holding the mutex across cancel_work_sync() makes the set-removing + drain step atomic. Every producer reaches the arming path from process context -- the PCIe firmware-halt notification runs in the threaded IRQ handler (brcmf_pcie_isr_thread) and the SDIO hostmail path runs from the data workqueue -- so the mutex is taken only in sleepable contexts. Where applicable the remove entry first stops the firmware-crash producer: on PCIe mask the mailbox and synchronize_irq; on SDIO unregister the bus interrupt and cancel the data worker, which also reports firmware halts through brcmf_fw_crashed(). The mutex is initialized at bus allocation. The SDIO suspend power-off path frees drvr through the same brcmf_sdiod_remove() and takes the same lock; resume re-allows the work only on a successful re-probe. Also guard brcmf_fw_crashed() against a NULL bus_if/drvr: it can fire before brcmf_attach() wires up drvr, and it dereferences drvr (bphy_err/brcmf_dev_coredump) before reaching the arming gate. The bus_reset work is shared across buses, so the drain is applied to every remove path: PCIe (the .reset op introduced by the Fixes commit), SDIO (arms the same work through brcmf_fw_crashed()), and USB (via the debugfs "reset" entry). cancel_work_sync() drains a running or pending bus_reset work item before removal frees drvr, and patch 1/2 makes the scratch-buffer release safe when reset teardown has already released those DMA buffers. This patch fixes the lifetime of the bus_reset work item itself. It does not attempt to address the separate, pre-existing lifetime of the asynchronous firmware completion started by the PCIe reset path. That callback needs its own lifetime/ownership protocol and is being tracked separately. This issue was found by an in-house static analysis tool. ## CVSS-Vektor ``` CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H ``` | Metrik | Wert | Bewertung | |---|---|---| | AV Angriffsvektor | Benachbart | warn | | AC Komplexität | Gering | bad | | PR Privilegien | Keine | bad | | UI Interaktion | Keine | bad | | S Scope | Unverändert | good | | C Vertraulichkeit | Hoch | bad | | I Integrität | Hoch | bad | | A Verfügbarkeit | Hoch | bad | ## Patch verfügbar (OSV) - Kernel ≥ 5.10.266 - Kernel ≥ 5.15.217 - Kernel ≥ 6.1.184 - Kernel ≥ 6.6.151 - Kernel ≥ 6.12.103 - Kernel ≥ 6.18.44 - Kernel ≥ 7.1.6 ## Referenzen - - - - - - - - --- _Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-64586) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_