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, 528 insertions, 0 deletions

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
new file mode 100644
index 000000000..cf499ba72
--- /dev/null
+++ b/fs/pstore/inode.c
@@ -0,0 +1,528 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Persistent Storage - ramfs parts.
+ *
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include <linux/seq_file.h>
+#include <linux/ramfs.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
+#include <linux/sched.h>
+#include <linux/magic.h>
+#include <linux/pstore.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/cleanup.h>
+
+#include "internal.h"
+
+#define	PSTORE_NAMELEN	64
+
+static DEFINE_MUTEX(records_list_lock);
+static LIST_HEAD(records_list);
+
+static DEFINE_MUTEX(pstore_sb_lock);
+static struct super_block *pstore_sb;
+
+DEFINE_FREE(pstore_iput, struct inode *, if (_T) iput(_T))
+
+struct pstore_private {
+	struct list_head list;
+	struct dentry *dentry;
+	struct pstore_record *record;
+	size_t total_size;
+};
+
+struct pstore_ftrace_seq_data {
+	const void *ptr;
+	size_t off;
+	size_t size;
+};
+
+#define REC_SIZE sizeof(struct pstore_ftrace_record)
+
+static void free_pstore_private(struct pstore_private *private)
+{
+	if (!private)
+		return;
+	if (private->record) {
+		kvfree(private->record->buf);
+		kfree(private->record->priv);
+		kfree(private->record);
+	}
+	kfree(private);
+}
+DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
+
+static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data __free(kfree) = NULL;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return NULL;
+
+	data->off = ps->record->size % REC_SIZE;
+	data->off += *pos * REC_SIZE;
+	if (data->off + REC_SIZE > ps->record->size)
+		return NULL;
+
+	return_ptr(data);
+}
+
+static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
+{
+	kfree(v);
+}
+
+static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+
+	(*pos)++;
+	data->off += REC_SIZE;
+	if (data->off + REC_SIZE > ps->record->size)
+		return NULL;
+
+	return data;
+}
+
+static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+	struct pstore_ftrace_record *rec;
+	unsigned long ip, parent_ip;
+
+	if (!data)
+		return 0;
+
+	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
+
+	ip = decode_ip(rec->ip);
+	parent_ip = decode_ip(rec->parent_ip);
+	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
+		   pstore_ftrace_decode_cpu(rec),
+		   pstore_ftrace_read_timestamp(rec),
+		   ip, parent_ip, (void *)ip, (void *)parent_ip);
+
+	return 0;
+}
+
+static const struct seq_operations pstore_ftrace_seq_ops = {
+	.start	= pstore_ftrace_seq_start,
+	.next	= pstore_ftrace_seq_next,
+	.stop	= pstore_ftrace_seq_stop,
+	.show	= pstore_ftrace_seq_show,
+};
+
+static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct seq_file *sf = file->private_data;
+	struct pstore_private *ps = sf->private;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		return seq_read(file, userbuf, count, ppos);
+	return simple_read_from_buffer(userbuf, count, ppos,
+				       ps->record->buf, ps->total_size);
+}
+
+static int pstore_file_open(struct inode *inode, struct file *file)
+{
+	struct pstore_private *ps = inode->i_private;
+	struct seq_file *sf;
+	int err;
+	const struct seq_operations *sops = NULL;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		sops = &pstore_ftrace_seq_ops;
+
+	err = seq_open(file, sops);
+	if (err < 0)
+		return err;
+
+	sf = file->private_data;
+	sf->private = ps;
+
+	return 0;
+}
+
+static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
+{
+	struct seq_file *sf = file->private_data;
+
+	if (sf->op)
+		return seq_lseek(file, off, whence);
+	return default_llseek(file, off, whence);
+}
+
+static const struct file_operations pstore_file_operations = {
+	.open		= pstore_file_open,
+	.read		= pstore_file_read,
+	.llseek		= pstore_file_llseek,
+	.release	= seq_release,
+};
+
+/*
+ * When a file is unlinked from our file system we call the
+ * platform driver to erase the record from persistent store.
+ */
+static int pstore_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct pstore_private *p = d_inode(dentry)->i_private;
+	struct pstore_record *record = p->record;
+
+	if (!record->psi->erase)
+		return -EPERM;
+
+	/* Make sure we can't race while removing this file. */
+	scoped_guard(mutex, &records_list_lock) {
+		if (!list_empty(&p->list))
+			list_del_init(&p->list);
+		else
+			return -ENOENT;
+		p->dentry = NULL;
+	}
+
+	scoped_guard(mutex, &record->psi->read_mutex)
+		record->psi->erase(record);
+
+	return simple_unlink(dir, dentry);
+}
+
+static void pstore_evict_inode(struct inode *inode)
+{
+	struct pstore_private	*p = inode->i_private;
+
+	clear_inode(inode);
+	free_pstore_private(p);
+}
+
+static const struct inode_operations pstore_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.unlink		= pstore_unlink,
+};
+
+static struct inode *pstore_get_inode(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		simple_inode_init_ts(inode);
+	}
+	return inode;
+}
+
+enum {
+	Opt_kmsg_bytes
+};
+
+static const struct fs_parameter_spec pstore_param_spec[] = {
+	fsparam_u32	("kmsg_bytes",	Opt_kmsg_bytes),
+	{}
+};
+
+struct pstore_context {
+	unsigned int kmsg_bytes;
+};
+
+static int pstore_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, pstore_param_spec, param, &result);
+	/* pstore has historically ignored invalid kmsg_bytes param */
+	if (opt < 0)
+		return 0;
+
+	switch (opt) {
+	case Opt_kmsg_bytes:
+		ctx->kmsg_bytes = result.uint_32;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int pstore_show_options(struct seq_file *m, struct dentry *root)
+{
+	if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
+		seq_printf(m, ",kmsg_bytes=%u", kmsg_bytes);
+	return 0;
+}
+
+static int pstore_reconfigure(struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+
+	sync_filesystem(fc->root->d_sb);
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	return 0;
+}
+
+static const struct super_operations pstore_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= inode_just_drop,
+	.evict_inode	= pstore_evict_inode,
+	.show_options	= pstore_show_options,
+};
+
+static struct dentry *psinfo_lock_root(void)
+{
+	struct dentry *root;
+
+	guard(mutex)(&pstore_sb_lock);
+	/*
+	 * Having no backend is fine -- no records appear.
+	 * Not being mounted is fine -- nothing to do.
+	 */
+	if (!psinfo || !pstore_sb)
+		return NULL;
+
+	root = pstore_sb->s_root;
+	inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
+
+	return root;
+}
+
+int pstore_put_backend_records(struct pstore_info *psi)
+{
+	struct pstore_private *pos, *tmp;
+	struct dentry *root;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return 0;
+
+	scoped_guard(mutex, &records_list_lock) {
+		list_for_each_entry_safe(pos, tmp, &records_list, list) {
+			if (pos->record->psi == psi) {
+				list_del_init(&pos->list);
+				locked_recursive_removal(pos->dentry, NULL);
+				pos->dentry = NULL;
+			}
+		}
+	}
+
+	inode_unlock(d_inode(root));
+
+	return 0;
+}
+
+/*
+ * Make a regular file in the root directory of our file system.
+ * Load it up with "size" bytes of data from "buf".
+ * Set the mtime & ctime to the date that this record was originally stored.
+ */
+int pstore_mkfile(struct dentry *root, struct pstore_record *record)
+{
+	struct dentry		*dentry;
+	struct inode		*inode __free(pstore_iput) = NULL;
+	char			name[PSTORE_NAMELEN];
+	struct pstore_private	*private __free(pstore_private) = NULL, *pos;
+	size_t			size = record->size + record->ecc_notice_size;
+
+	if (WARN_ON(!inode_is_locked(d_inode(root))))
+		return -EINVAL;
+
+	guard(mutex)(&records_list_lock);
+
+	/* Skip records that are already present in the filesystem. */
+	list_for_each_entry(pos, &records_list, list) {
+		if (pos->record->type == record->type &&
+		    pos->record->id == record->id &&
+		    pos->record->psi == record->psi)
+			return -EEXIST;
+	}
+
+	inode = pstore_get_inode(root->d_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode->i_mode = S_IFREG | 0444;
+	inode->i_fop = &pstore_file_operations;
+	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
+			pstore_type_to_name(record->type),
+			record->psi->name, record->id,
+			record->compressed ? ".enc.z" : "");
+
+	private = kzalloc_obj(*private);
+	if (!private)
+		return -ENOMEM;
+
+	dentry = d_alloc_name(root, name);
+	if (!dentry)
+		return -ENOMEM;
+
+	private->dentry = dentry; // borrowed
+	private->record = record;
+	inode->i_size = private->total_size = size;
+	inode->i_private = private;
+
+	if (record->time.tv_sec)
+		inode_set_mtime_to_ts(inode,
+				      inode_set_ctime_to_ts(inode, record->time));
+
+	d_make_persistent(dentry, no_free_ptr(inode));
+	dput(dentry);
+
+	list_add(&(no_free_ptr(private))->list, &records_list);
+
+	return 0;
+}
+
+/*
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_records(int quiet)
+{
+	struct dentry *root;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return;
+
+	pstore_get_backend_records(psinfo, root, quiet);
+	inode_unlock(d_inode(root));
+}
+
+static int pstore_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	struct inode *inode;
+
+	sb->s_maxbytes		= MAX_LFS_FILESIZE;
+	sb->s_blocksize		= PAGE_SIZE;
+	sb->s_blocksize_bits	= PAGE_SHIFT;
+	sb->s_magic		= PSTOREFS_MAGIC;
+	sb->s_op		= &pstore_ops;
+	sb->s_time_gran		= 1;
+
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	inode = pstore_get_inode(sb);
+	if (inode) {
+		inode->i_mode = S_IFDIR | 0750;
+		inode->i_op = &pstore_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+		inc_nlink(inode);
+	}
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	scoped_guard(mutex, &pstore_sb_lock)
+		pstore_sb = sb;
+
+	pstore_get_records(0);
+
+	return 0;
+}
+
+static int pstore_get_tree(struct fs_context *fc)
+{
+	if (fc->root)
+		return pstore_reconfigure(fc);
+
+	return get_tree_single(fc, pstore_fill_super);
+}
+
+static void pstore_free_fc(struct fs_context *fc)
+{
+	kfree(fc->fs_private);
+}
+
+static const struct fs_context_operations pstore_context_ops = {
+	.parse_param	= pstore_parse_param,
+	.get_tree	= pstore_get_tree,
+	.reconfigure	= pstore_reconfigure,
+	.free		= pstore_free_fc,
+};
+
+static void pstore_kill_sb(struct super_block *sb)
+{
+	guard(mutex)(&pstore_sb_lock);
+	WARN_ON(pstore_sb && pstore_sb != sb);
+
+	kill_anon_super(sb);
+	pstore_sb = NULL;
+
+	guard(mutex)(&records_list_lock);
+	INIT_LIST_HEAD(&records_list);
+}
+
+static int pstore_init_fs_context(struct fs_context *fc)
+{
+	struct pstore_context *ctx;
+
+	ctx = kzalloc_obj(struct pstore_context);
+	if (!ctx)
+		return -ENOMEM;
+
+	/*
+	 * Global kmsg_bytes is initialized to default, and updated
+	 * every time we (re)mount the single-sb filesystem with the
+	 * option specified.
+	 */
+	ctx->kmsg_bytes = kmsg_bytes;
+
+	fc->fs_private = ctx;
+	fc->ops = &pstore_context_ops;
+
+	return 0;
+}
+
+static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
+	.name		= "pstore",
+	.kill_sb	= pstore_kill_sb,
+	.init_fs_context = pstore_init_fs_context,
+	.parameters	= pstore_param_spec,
+};
+
+int __init pstore_init_fs(void)
+{
+	int err;
+
+	/* Create a convenient mount point for people to access pstore */
+	err = sysfs_create_mount_point(fs_kobj, "pstore");
+	if (err)
+		goto out;
+
+	err = register_filesystem(&pstore_fs_type);
+	if (err < 0)
+		sysfs_remove_mount_point(fs_kobj, "pstore");
+
+out:
+	return err;
+}
+
+void __exit pstore_exit_fs(void)
+{
+	unregister_filesystem(&pstore_fs_type);
+	sysfs_remove_mount_point(fs_kobj, "pstore");
+}