Linux Kernel PCI Generic MHI Host Deadlock Vulnerability

A deadlock vulnerability has been identified in the Linux kernel's PCI generic MHI host bus management. This issue arises during the asynchronous scheduling of recovery work, which can conflict with synchronous wait times for recovery completion. A specific scenario involves the PM shutdown callback, where the driver core holds the device lock while calling the shutdown function. If the device has already died and recovery work is in progress, the attempt to reset the device can become stalled, leading to a deadlock. This problem has been observed with the X1E80100 CRD device, but could potentially affect other devices under similar conditions.

Impact

Exploitation of this vulnerability leads to a deadlock, causing the system to hang while waiting for a locked resource to become available.

Remediation

The vulnerability has been addressed by modifying the recovery process to use 'pci_try_reset_function()', which checks the availability of the device lock before attempting a reset. This change prevents the deadlock by ensuring that the recovery work does not interfere with other operations that require the device lock.