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.

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: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 120 more

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.