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CVE-2025-39884 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix subvolume deletion lockup caused by inodes xarray race There is a race condition between inode eviction and inode caching that can cause a live struct btrfs_inode to be missing from the root->inodes xarray. Specifically, there is a window during evict() between the inode being unhashed and deleted from the xarray. If btrfs_iget() is called for the same inode in that window, it will be recreated and inserted into the xarray, but then eviction will delete the new entry, leaving nothing in the xarray: Thread 1 Thread 2 --------------------------------------------------------------- evict() remove_inode_hash() btrfs_iget_path() btrfs_iget_locked() btrfs_read_locked_inode() btrfs_add_inode_to_root() destroy_inode() btrfs_destroy_inode() btrfs_del_inode_from_root() __xa_erase In turn, this can cause issues for subvolume deletion. Specifically, if an inode is in this lost state, and all other inodes are evicted, then btrfs_del_inode_from_root() will call btrfs_add_dead_root() prematurely. If the lost inode has a delayed_node attached to it, then when btrfs_clean_one_deleted_snapshot() calls btrfs_kill_all_delayed_nodes(), it will loop forever because the delayed_nodes xarray will never become empty (unless memory pressure forces the inode out). We saw this manifest as soft lockups in production. Fix it by only deleting the xarray entry if it matches the given inode (using __xa_cmpxchg()).


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/9ba898c9fcbe6ebb88bcd4df8aab0f90090d202e kernel.org
https://git.kernel.org/stable/c/f1498abaf74f8d7b1e7001f16ed77818d8ae6a59 kernel.org
https://git.kernel.org/stable/c/f6a6c280059c4ddc23e12e3de1b01098e240036f kernel.org

Weakness Enumeration

CWE-ID CWE Name Source

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-39884
NVD Published Date:
09/23/2025
NVD Last Modified:
09/23/2025
Source:
kernel.org