CVE-2026-97949: configfs: unhash the dentry before dropping the item in rmdir
configfs: unhash the dentry before dropping the item in rmdir
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
azurelinux/kernelto a version that resolves this vulnerability.Fixed in 6.6.161.1-1 - Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.116-1Fixed in 7.2.15-1Fixed in 7.3.3-1 - Upgrade
Upgrade
debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.115-2~deb12u1 - Compensating control
Modify Linux kernel configfs rmdir handling to unhash the dentry in configfs_remove_dir() before dropping the config_item, so configfs_get_config_item() cannot treat a stale hashed dentry as a live item.
Event History
Frequently Asked Questions
What conditions are needed to trigger the use-after-free?
The race requires a configfs directory removal and configfs symlink target resolution to overlap. During the window after simple_rmdir() drops the item's last reference but before d_delete() unhashes the dentry, get_target() can treat the still-hashed dentry as referring to a live config_item.
Which systems are realistically exposed?
Systems using configfs are exposed when configfs rmdir activity can occur concurrently with configfs symlink creation or target lookup. The provided data does not state whether configfs is enabled or used by default on any particular system.
How might this appear during testing or investigation?
The reported manifestation is a KASAN slab-use-after-free in config_item_get(), reached through get_target() during configfs_symlink(). The trace identifies fs/configfs/symlink.c as the target-resolution path involved.
What does the fix change?
The fix unhashed the dentry in configfs_remove_dir() while the config_item is still guaranteed to exist, rather than waiting for d_delete() after rmdir returns. A reference acquired immediately before removal remains harmless because create_link() rechecks CONFIGFS_USET_DROPPING.