| Description | 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. |