CVE-2024-26806

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

spi: cadence-qspi: remove system-wide suspend helper calls from runtime PM hooks

The ->runtime_suspend() and ->runtime_resume() callbacks are not

expected to call spi_controller_suspend() and spi_controller_resume().

Remove calls to those in the cadence-qspi driver.

Those helpers have two roles currently:

- They stop/start the queue, including dealing with the kworker.

- They toggle the SPI controller SPI_CONTROLLER_SUSPENDED flag. It

requires acquiring ctlr->bus_lock_mutex.

Step one is irrelevant because cadence-qspi is not queued. Step two

however has two implications:

- A deadlock occurs, because ->runtime_resume() is called in a context

where the lock is already taken (in the ->exec_op() callback, where

the usage count is incremented).

- It would disallow all operations once the device is auto-suspended.

Here is a brief call tree highlighting the mutex deadlock:

spi_mem_exec_op()

...

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References