ocfs2: fix circular locking dependency in ocfs2_init_acl()

Summary

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix circular locking dependency in ocfs2_init_acl() A lockdep warning indicates a circular locking dependency between `&oi->ip_xattr_sem` and `&journal->j_trans_barrier`: WARNING: possible circular locking dependency detected is trying to acquire lock: (&oi->ip_xattr_sem){++++}-{4:4}, at: ocfs2_init_acl+0x2fd/0x7e0 fs/ocfs2/acl.c:367 but task is already holding lock: (&journal->j_trans_barrier){.+.+}-{4:4}, at: ocfs2_start_trans+0x3ab/0x700 fs/ocfs2/journal.c:369 The deadlock involves two code paths: Path 1 (setxattr) where `ocfs2_xattr_set()` acquires `ip_xattr_sem` (write) and then starts a transaction, which acquires `j_trans_barrier` (read); and Path 2 (mkdir/mknod) where `ocfs2_mknod()` starts a transaction (`j_trans_barrier` read) and then calls `ocfs2_init_acl()`, which attempts to acquire `ip_xattr_sem` (read) on the parent directory to retrieve the default ACL. Because rw_semaphores are subject to writer priority, a pending writer on `j_trans_barrier` (e.g., the journal commit thread) can cause Path 1 to block, while Path 2 is blocked waiting for Path 1 to release `ip_xattr_sem`. The patch fixes the lock ordering by precomputing the ACL state before starting the OCFS2 transaction, while preserving POSIX ACL storage semantics and the existing inode/security initialization order. By reading the parent directory's default ACL and preparing the new inode's ACLs outside the transaction, `ip_xattr_sem` is always acquired before `j_trans_barrier`. `struct ocfs2_acl_state` encapsulates the prepared ACL state, while `ocfs2_acl_init_prepare()` and `ocfs2_acl_init_release()` avoid code duplication between `ocfs2_mknod()` and `ocfs2_init_security_and_acl()`. `ocfs2_calc_xattr_init()` and `ocfs2_init_acl()` use this precomputed state, removing internal `ip_xattr_sem` acquisition and redundant disk reads. Additionally, remove the `ip_xattr_sem` acquisition from `ocfs2_xattr_set_handle()`. This function is only used while initializing a new inode that has not yet been inserted into the inode hash or attached to a dentry, meaning there is no risk of concurrent access and the lock is unnecessary.

Timeline

1. Sep 24, 2026, 3:51 PM UTCCVE published
2. Oct 19, 2026, 9:08 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in 4936d4464d1ae10b5fbba64374085a0dcc060560; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in caf3056936fb8b5ce92e419cf8b246ce9c437343; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in 5b7b3c50c39ad0dc27e7418981e01c4183273f89; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in 8d88f52fbbbcc18adf4091a955511d0cf605bf11; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in 8931403ee3dcfe8a24a5267efec9d9460ab7a1b5; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in f8747d81aa6d3efe3ee339a9d912ff3ca6e4d758; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in 1222f7a3183b35c0c566899fdaead5c7c4043076; From 16c8d569f5704a84164f30ff01b29879f3438065 · fixed in bd7c05fb4a4776dff5a87b19008d28458647d15d; From 3.18.111 · fixed in 3.19; From 4.4.134 · fixed in 4.5; From 4.9.104 · fixed in 4.10; From 4.14.37 · fixed in 4.15

• Linux Linux

  4.16

• KernelLinux

  From 4.16.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6

References 8