CVE-2026-89491

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

ocfs2: cluster: don't sleep while holding o2hb_live_lock in o2hb_region_pin()

Patch series "ocfs2: cluster: o2hb_region_pin() fixes", v2.

This series fixes three related issues in o2hb_region_pin(), all are from

the original implementation in commit: 58a3158a5d17 ("ocfs2/cluster:

Pin/unpin o2hb regions"):

1) It is called with o2hb_live_lock (a spinlock) held, but the

underlying configfs_depend_item() sleeps (takes inode rwsem and

pins the filesystem). This triggers BUG under

CONFIG_DEBUG_ATOMIC_SLEEP.

2) When called from the configfs drop_item callback, it creates a

lock order inversion: parent inode_lock -> configfs root

inode_lock, which can deadlock against subsystem unregistration

paths taking root -> parent.

3) If pinning fails partway through o2hb_region_inc_user(), the

o2hb_dependent_users counter is leaked and partially-pinned

regions are never released, leaving heartbeat regions

unprotected on subsequent mounts.

Patch 1 reworks o2hb_region_pin() to drop o2hb_live_lock across each

sleeping configfs_depend_item() call, using a config_item reference to

keep the region alive while unlocked.

Patch 2 adds a from_callback parameter to select

configfs_depend_item_unlocked() when called from configfs context,

avoiding the inode_lock nesting.

Patch 3 fixes the error path in o2hb_region_inc_user() to unpin and

decrement the counter on failure.

This patch (of 3):

o2hb_region_pin() is always called with the o2hb_live_lock spinlock held

(from o2hb_region_inc_user() and o2hb_heartbeat_group_drop_item()), but it

calls o2nm_depend_item() -> configfs_depend_item(), which sleeps: it pins

the configfs filesystem and takes the configfs root inode rwsem. Under

CONFIG_DEBUG_ATOMIC_SLEEP this triggers:

BUG: sleeping function called from invalid context at kernel/locking/rwsem.c

in_atomic(): 1, ... name: mount.ocfs2

down_write

configfs_depend_item

o2hb_region_pin

o2hb_region_inc_user

o2hb_register_callback

dlm_register_domain_handlers

...

ocfs2_dlm_init

ocfs2_mount_volume

ocfs2_fill_super

Rework o2hb_region_pin() to pin one region at a time with the lock dropped

across the sleeping call: under o2hb_live_lock find the next eligible

region and take a config_item reference to keep it alive, drop the lock,

call o2nm_depend_item(), then retake the lock and record the pin. The

config_item_put() is done with the lock released as well, since

o2hb_region_release() also acquires o2hb_live_lock and can sleep. The

region list may change while unlocked, so the scan restarts from the top

after each pin. Local heartbeat still pins only the matching region;

global heartbeat pins all eligible regions.

The unpin path is unaffected: configfs_undepend_item() only takes a

spinlock and does not sleep.