Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 472 insertions, 0 deletions

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
new file mode 100644
index 000000000..f183a9677
--- /dev/null
+++ b/fs/kernfs/mount.c
@@ -0,0 +1,472 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * fs/kernfs/mount.c - kernfs mount implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/init.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/seq_file.h>
+#include <linux/exportfs.h>
+#include <linux/uuid.h>
+#include <linux/statfs.h>
+
+#include "kernfs-internal.h"
+
+struct kmem_cache *kernfs_node_cache __ro_after_init;
+struct kmem_cache *kernfs_iattrs_cache __ro_after_init;
+struct kernfs_global_locks *kernfs_locks __ro_after_init;
+
+static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
+{
+	struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
+	struct kernfs_syscall_ops *scops = root->syscall_ops;
+
+	if (scops && scops->show_options)
+		return scops->show_options(sf, root);
+	return 0;
+}
+
+static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
+{
+	struct kernfs_node *node = kernfs_dentry_node(dentry);
+	struct kernfs_root *root = kernfs_root(node);
+	struct kernfs_syscall_ops *scops = root->syscall_ops;
+
+	if (scops && scops->show_path)
+		return scops->show_path(sf, node, root);
+
+	seq_dentry(sf, dentry, " \t\n\\");
+	return 0;
+}
+
+static int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	simple_statfs(dentry, buf);
+	buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
+	return 0;
+}
+
+const struct super_operations kernfs_sops = {
+	.statfs		= kernfs_statfs,
+	.drop_inode	= inode_just_drop,
+	.evict_inode	= kernfs_evict_inode,
+
+	.show_options	= kernfs_sop_show_options,
+	.show_path	= kernfs_sop_show_path,
+
+	/*
+	 * sysfs is built on top of kernfs and sysfs provides the power
+	 * management infrastructure to support suspend/hibernate by
+	 * writing to various files in /sys/power/. As filesystems may
+	 * be automatically frozen during suspend/hibernate implementing
+	 * freeze/thaw support for kernfs generically will cause
+	 * deadlocks as the suspending/hibernation initiating task will
+	 * hold a VFS lock that it will then wait upon to be released.
+	 * If freeze/thaw for kernfs is needed talk to the VFS.
+	 */
+	.freeze_fs	= NULL,
+	.unfreeze_fs	= NULL,
+	.freeze_super	= NULL,
+	.thaw_super	= NULL,
+};
+
+static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,
+			    struct inode *parent)
+{
+	struct kernfs_node *kn = inode->i_private;
+
+	if (*max_len < 2) {
+		*max_len = 2;
+		return FILEID_INVALID;
+	}
+
+	*max_len = 2;
+	*(u64 *)fh = kn->id;
+	return FILEID_KERNFS;
+}
+
+static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb,
+					    struct fid *fid, int fh_len,
+					    int fh_type, bool get_parent)
+{
+	struct kernfs_super_info *info = kernfs_info(sb);
+	struct kernfs_node *kn;
+	struct inode *inode;
+	u64 id;
+
+	if (fh_len < 2)
+		return NULL;
+
+	switch (fh_type) {
+	case FILEID_KERNFS:
+		id = *(u64 *)fid;
+		break;
+	case FILEID_INO32_GEN:
+	case FILEID_INO32_GEN_PARENT:
+		/*
+		 * blk_log_action() exposes "LOW32,HIGH32" pair without
+		 * type and userland can call us with generic fid
+		 * constructed from them.  Combine it back to ID.  See
+		 * blk_log_action().
+		 */
+		id = ((u64)fid->i32.gen << 32) | fid->i32.ino;
+		break;
+	default:
+		return NULL;
+	}
+
+	kn = kernfs_find_and_get_node_by_id(info->root, id);
+	if (!kn)
+		return ERR_PTR(-ESTALE);
+
+	if (get_parent) {
+		struct kernfs_node *parent;
+
+		parent = kernfs_get_parent(kn);
+		kernfs_put(kn);
+		kn = parent;
+		if (!kn)
+			return ERR_PTR(-ESTALE);
+	}
+
+	inode = kernfs_get_inode(sb, kn);
+	kernfs_put(kn);
+	return d_obtain_alias(inode);
+}
+
+static struct dentry *kernfs_fh_to_dentry(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, false);
+}
+
+static struct dentry *kernfs_fh_to_parent(struct super_block *sb,
+					  struct fid *fid, int fh_len,
+					  int fh_type)
+{
+	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, true);
+}
+
+static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
+{
+	struct kernfs_node *kn = kernfs_dentry_node(child);
+	struct kernfs_root *root = kernfs_root(kn);
+
+	guard(rwsem_read)(&root->kernfs_rwsem);
+	return d_obtain_alias(kernfs_get_inode(child->d_sb, kernfs_parent(kn)));
+}
+
+static const struct export_operations kernfs_export_ops = {
+	.encode_fh	= kernfs_encode_fh,
+	.fh_to_dentry	= kernfs_fh_to_dentry,
+	.fh_to_parent	= kernfs_fh_to_parent,
+	.get_parent	= kernfs_get_parent_dentry,
+};
+
+/**
+ * kernfs_root_from_sb - determine kernfs_root associated with a super_block
+ * @sb: the super_block in question
+ *
+ * Return: the kernfs_root associated with @sb.  If @sb is not a kernfs one,
+ * %NULL is returned.
+ */
+struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
+{
+	if (sb->s_op == &kernfs_sops)
+		return kernfs_info(sb)->root;
+	return NULL;
+}
+
+/*
+ * find the next ancestor in the path down to @child, where @parent was the
+ * ancestor whose descendant we want to find.
+ *
+ * Say the path is /a/b/c/d.  @child is d, @parent is %NULL.  We return the root
+ * node.  If @parent is b, then we return the node for c.
+ * Passing in d as @parent is not ok.
+ */
+static struct kernfs_node *find_next_ancestor(struct kernfs_node *child,
+					      struct kernfs_node *parent)
+{
+	if (child == parent) {
+		pr_crit_once("BUG in find_next_ancestor: called with parent == child");
+		return NULL;
+	}
+
+	while (kernfs_parent(child) != parent) {
+		child = kernfs_parent(child);
+		if (!child)
+			return NULL;
+	}
+
+	return child;
+}
+
+/**
+ * kernfs_node_dentry - get a dentry for the given kernfs_node
+ * @kn: kernfs_node for which a dentry is needed
+ * @sb: the kernfs super_block
+ *
+ * Return: the dentry pointer
+ */
+struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
+				  struct super_block *sb)
+{
+	struct dentry *dentry;
+	struct kernfs_node *knparent;
+	struct kernfs_root *root;
+
+	BUG_ON(sb->s_op != &kernfs_sops);
+
+	dentry = dget(sb->s_root);
+
+	/* Check if this is the root kernfs_node */
+	if (!rcu_access_pointer(kn->__parent))
+		return dentry;
+
+	root = kernfs_root(kn);
+	/*
+	 * As long as kn is valid, its parent can not vanish. This is cgroup's
+	 * kn so it can't have its parent replaced. Therefore it is safe to use
+	 * the ancestor node outside of the RCU or locked section.
+	 */
+	if (WARN_ON_ONCE(!(root->flags & KERNFS_ROOT_INVARIANT_PARENT)))
+		return ERR_PTR(-EINVAL);
+	scoped_guard(rcu) {
+		knparent = find_next_ancestor(kn, NULL);
+	}
+	if (WARN_ON(!knparent)) {
+		dput(dentry);
+		return ERR_PTR(-EINVAL);
+	}
+
+	do {
+		struct dentry *dtmp;
+		struct kernfs_node *kntmp;
+		const char *name;
+
+		if (kn == knparent)
+			return dentry;
+
+		scoped_guard(rwsem_read, &root->kernfs_rwsem) {
+			kntmp = find_next_ancestor(kn, knparent);
+			if (WARN_ON(!kntmp)) {
+				dput(dentry);
+				return ERR_PTR(-EINVAL);
+			}
+			name = kstrdup(kernfs_rcu_name(kntmp), GFP_KERNEL);
+		}
+		if (!name) {
+			dput(dentry);
+			return ERR_PTR(-ENOMEM);
+		}
+		dtmp = lookup_noperm_positive_unlocked(&QSTR(name), dentry);
+		dput(dentry);
+		kfree(name);
+		if (IS_ERR(dtmp))
+			return dtmp;
+		knparent = kntmp;
+		dentry = dtmp;
+	} while (true);
+}
+
+static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
+{
+	struct kernfs_super_info *info = kernfs_info(sb);
+	struct kernfs_root *kf_root = kfc->root;
+	struct inode *inode;
+	struct dentry *root;
+
+	info->sb = sb;
+	/* Userspace would break if executables or devices appear on sysfs */
+	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
+	sb->s_blocksize = PAGE_SIZE;
+	sb->s_blocksize_bits = PAGE_SHIFT;
+	sb->s_magic = kfc->magic;
+	sb->s_op = &kernfs_sops;
+	sb->s_xattr = kernfs_xattr_handlers;
+	if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
+		sb->s_export_op = &kernfs_export_ops;
+	sb->s_time_gran = 1;
+	sb->s_maxbytes  = MAX_LFS_FILESIZE;
+
+	/* sysfs dentries and inodes don't require IO to create */
+	sb->s_shrink->seeks = 0;
+
+	/* get root inode, initialize and unlock it */
+	down_read(&kf_root->kernfs_rwsem);
+	inode = kernfs_get_inode(sb, info->root->kn);
+	up_read(&kf_root->kernfs_rwsem);
+	if (!inode) {
+		pr_debug("kernfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	/* instantiate and link root dentry */
+	root = d_make_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n", __func__);
+		return -ENOMEM;
+	}
+	sb->s_root = root;
+	set_default_d_op(sb, &kernfs_dops);
+	return 0;
+}
+
+static int kernfs_test_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct kernfs_super_info *sb_info = kernfs_info(sb);
+	struct kernfs_super_info *info = fc->s_fs_info;
+
+	return sb_info->root == info->root && sb_info->ns == info->ns;
+}
+
+static int kernfs_set_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct kernfs_fs_context *kfc = fc->fs_private;
+
+	kfc->ns_tag = NULL;
+	return set_anon_super_fc(sb, fc);
+}
+
+/**
+ * kernfs_super_ns - determine the namespace tag of a kernfs super_block
+ * @sb: super_block of interest
+ *
+ * Return: the namespace tag associated with kernfs super_block @sb.
+ */
+const struct ns_common *kernfs_super_ns(struct super_block *sb)
+{
+	struct kernfs_super_info *info = kernfs_info(sb);
+
+	return info->ns;
+}
+
+/**
+ * kernfs_get_tree - kernfs filesystem access/retrieval helper
+ * @fc: The filesystem context.
+ *
+ * This is to be called from each kernfs user's fs_context->ops->get_tree()
+ * implementation, which should set the specified ->@fs_type and ->@flags, and
+ * specify the hierarchy and namespace tag to mount via ->@root and ->@ns,
+ * respectively.
+ *
+ * Return: %0 on success, -errno on failure.
+ */
+int kernfs_get_tree(struct fs_context *fc)
+{
+	struct kernfs_fs_context *kfc = fc->fs_private;
+	struct super_block *sb;
+	struct kernfs_super_info *info;
+	int error;
+
+	info = kzalloc_obj(*info);
+	if (!info)
+		return -ENOMEM;
+
+	info->root = kfc->root;
+	info->ns = kfc->ns_tag;
+	INIT_LIST_HEAD(&info->node);
+
+	fc->s_fs_info = info;
+	sb = sget_fc(fc, kernfs_test_super, kernfs_set_super);
+	if (IS_ERR(sb))
+		return PTR_ERR(sb);
+
+	if (!sb->s_root) {
+		struct kernfs_super_info *info = kernfs_info(sb);
+		struct kernfs_root *root = kfc->root;
+
+		kfc->new_sb_created = true;
+
+		error = kernfs_fill_super(sb, kfc);
+		if (error) {
+			deactivate_locked_super(sb);
+			return error;
+		}
+		sb->s_flags |= SB_ACTIVE;
+
+		uuid_t uuid;
+		uuid_gen(&uuid);
+		super_set_uuid(sb, uuid.b, sizeof(uuid));
+
+		down_write(&root->kernfs_supers_rwsem);
+		list_add(&info->node, &info->root->supers);
+		up_write(&root->kernfs_supers_rwsem);
+	}
+
+	fc->root = dget(sb->s_root);
+	return 0;
+}
+
+void kernfs_free_fs_context(struct fs_context *fc)
+{
+	/* Note that we don't deal with kfc->ns_tag here. */
+	kfree(fc->s_fs_info);
+	fc->s_fs_info = NULL;
+}
+
+/**
+ * kernfs_kill_sb - kill_sb for kernfs
+ * @sb: super_block being killed
+ *
+ * This can be used directly for file_system_type->kill_sb().  If a kernfs
+ * user needs extra cleanup, it can implement its own kill_sb() and call
+ * this function at the end.
+ */
+void kernfs_kill_sb(struct super_block *sb)
+{
+	struct kernfs_super_info *info = kernfs_info(sb);
+	struct kernfs_root *root = info->root;
+
+	down_write(&root->kernfs_supers_rwsem);
+	list_del(&info->node);
+	up_write(&root->kernfs_supers_rwsem);
+
+	/*
+	 * Remove the superblock from fs_supers/s_instances
+	 * so we can't find it, before freeing kernfs_super_info.
+	 */
+	kill_anon_super(sb);
+	kfree(info);
+}
+
+static void __init kernfs_mutex_init(void)
+{
+	int count;
+
+	for (count = 0; count < NR_KERNFS_LOCKS; count++)
+		mutex_init(&kernfs_locks->node_mutex[count]);
+}
+
+static void __init kernfs_lock_init(void)
+{
+	kernfs_locks = kmalloc_obj(struct kernfs_global_locks);
+	WARN_ON(!kernfs_locks);
+
+	kernfs_mutex_init();
+}
+
+void __init kernfs_init(void)
+{
+	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
+					      sizeof(struct kernfs_node),
+					      0, SLAB_PANIC, NULL);
+
+	/* Creates slab cache for kernfs inode attributes */
+	kernfs_iattrs_cache  = kmem_cache_create("kernfs_iattrs_cache",
+					      sizeof(struct kernfs_iattrs),
+					      0, SLAB_PANIC, NULL);
+
+	kernfs_lock_init();
+}