CVE-2022-49079

/// Technical description

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

btrfs: zoned: traverse devices under chunk_mutex in btrfs_can_activate_zone

btrfs_can_activate_zone() can be called with the device_list_mutex already

held, which will lead to a deadlock:

insert_dev_extents() // Takes device_list_mutex

`-> insert_dev_extent()

`-> btrfs_insert_empty_item()

`-> btrfs_insert_empty_items()

`-> btrfs_search_slot()

`-> btrfs_cow_block()

`-> __btrfs_cow_block()

`-> btrfs_alloc_tree_block()

`-> btrfs_reserve_extent()

`-> find_free_extent()

`-> find_free_extent_update_loop()

`-> can_allocate_chunk()

`-> btrfs_can_activate_zone() // Takes device_list_mutex again

Instead of using the RCU on fs_devices->device_list we

can use fs_devices->alloc_list, protected by the chunk_mutex to traverse

the list of active devices.

We are in the chunk allocation thread. The newer chunk allocation

happens from the devices in the fs_device->all

/// 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