CVE-2024-57946

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

virtio-blk: don't keep queue frozen during system suspend

Commit 4ce6e2db00de ("virtio-blk: Ensure no requests in virtqueues before deleting vqs.") replaces queue quiesce with queue freeze in virtio-blk's PM callbacks. And the motivation is to drain inflight IOs before suspending.

block layer's queue freeze looks very handy, but it is also easy to cause deadlock, such as, any attempt to call into bio_queue_enter() may run into deadlock if the queue is frozen in current context. There are all kinds of ->suspend() called in suspend context, so keeping queue frozen in the whole suspend context isn't one good idea. And Marek reported lockdep warning[1] caused by virtio-blk's freeze queue in virtblk_freeze().

[1] https://lore.kernel.org/linux-block/[email protected]/

Given the motivation is to drain in-flight IOs, it can be done by calling freeze & unfreeze, meantime restore to previous behavior by keeping queue quiesced during suspend.

This vulnerability is rated as Moderate severity because triggering the deadlock requires elevated privileges to initiate a system suspend operation, limiting the impact to a local denial of service. The issue affects virtual guest systems utilizing virtio-blk devices during system suspend or power management transitions. Because system suspend is rarely performed in enterprise server and cloud deployments, and normal storage operations remain unaffected outside of suspend workflows, the operational exposure is substantially minimized.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.