bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir

Overview

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

bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir

bpf_lsm_has_d_inode_locked() makes the verifier rewrite bpf_[set|remove]_dentry_xattr() to the _locked variants, which assume that the caller already holds the inode's i_rwsem. The path_unlink and path_rmdir hooks are listed, but security_path_unlink() and security_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the victim inode's i_rwsem, so a sleepable BPF LSM program attached to either hook mutates the victim's xattrs without the lock held.

Drop the two path hooks from d_inode_locked_hooks so that the verifier keeps the locking bpf_[set|remove]_dentry_xattr() variants, which take the lock themselves.

Affected

• Linux >= 56467292794b800164df20c076c409ac548e56ec < 7504b677c4370c9e4b153c553ff8831c093b1ff6
• Linux >= 56467292794b800164df20c076c409ac548e56ec < 640d37fbd34d03af727dbc567f48c0203d1de6b4
• Linux >= 56467292794b800164df20c076c409ac548e56ec < 35d442ed1f86465e49df3119fb898f985186db13
• Linux 6.15

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.