wifi: brcmfmac: drain bus_reset work on device removal

Summary

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.

Timeline

1. Aug 6, 2026, 7:06 AM UTCCVE published
2. Oct 16, 2026, 3:43 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 8:48 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 9dfb09cb0abbf92a06f93e0715e163aa188a84da; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 4824e3bcc68f8d678b409039d1bb48c7b5ea73dc; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 61127dd20920bf28460a1609aabb0dafa2f54fac; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in c268331845ee00dbdbccb000826bb612dff2bee7; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in e3815d1ffbb9be4f1605ddc3b427557893461683; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 02d378828af8bb74f6c2f4d2bee3c77cf16c861e; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 177a25be1195f8bdc6160ba5f1a5699f7041c985; From 4684997d9eea29380000e062755aa6d368d789a3 · fixed in 43b25879f004c98defa2776bedc6ca4763c51945

• Linux Linux

  5.2

• KernelLinux

  From 5.2.0 · fixed in 5.10.266; From 5.11.0 · fixed in 5.15.217; From 5.16.0 · fixed in 6.1.184; From 6.2.0 · fixed in 6.6.151; From 6.7.0 · fixed in 6.12.103; From 6.13.0 · fixed in 6.18.44; From 6.19.0 · fixed in 7.1.6

References 8