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.

https://git.kernel.org/stable/c/177a25be1195f8bdc6160ba5f1a5699f7041c985

https://git.kernel.org/stable/c/43b25879f004c98defa2776bedc6ca4763c51945

[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/bus.h","drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.h","drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"4684997d9eea29380000e062755aa6d368d789a3","lessThan":"177a25be1195f8bdc6160ba5f1a5699f7041c985","versionType":"git","status":"affected"},{"version":"4684997d9eea29380000e062755aa6d368d789a3","lessThan":"43b25879f004c98defa2776bedc6ca4763c51945","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/bus.h","drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c","drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.h","drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"5.2","status":"affected"},{"version":"0","lessThan":"5.2","versionType":"semver","status":"unaffected"},{"version":"7.1.6","lessThanOrEqual":"7.1.*","versionType":"semver","status":"unaffected"},{"version":"7.2-rc5","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]