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, 481 insertions, 0 deletions

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
new file mode 100644
index 000000000..a48cece77
--- /dev/null
+++ b/fs/configfs/file.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * file.c - operations for regular (text) files.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/vmalloc.h>
+#include <linux/uaccess.h>
+#include <linux/uio.h>
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+/*
+ * A simple attribute can only be 4096 characters.  Why 4k?  Because the
+ * original code limited it to PAGE_SIZE.  That's a bad idea, though,
+ * because an attribute of 16k on ia64 won't work on x86.  So we limit to
+ * 4k, our minimum common page size.
+ */
+#define SIMPLE_ATTR_SIZE 4096
+
+struct configfs_buffer {
+	size_t			count;
+	loff_t			pos;
+	char			* page;
+	const struct configfs_item_operations	*ops;
+	struct mutex		mutex;
+	int			needs_read_fill;
+	bool			read_in_progress;
+	bool			write_in_progress;
+	char			*bin_buffer;
+	int			bin_buffer_size;
+	int			cb_max_size;
+	struct config_item	*item;
+	struct module		*owner;
+	union {
+		struct configfs_attribute	*attr;
+		struct configfs_bin_attribute	*bin_attr;
+	};
+};
+
+static inline struct configfs_fragment *to_frag(struct file *file)
+{
+	struct configfs_dirent *sd = file->f_path.dentry->d_fsdata;
+
+	return sd->s_frag;
+}
+
+static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
+{
+	struct configfs_fragment *frag = to_frag(file);
+	ssize_t count = -ENOENT;
+
+	if (!buffer->page)
+		buffer->page = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	down_read(&frag->frag_sem);
+	if (!frag->frag_dead)
+		count = buffer->attr->show(buffer->item, buffer->page);
+	up_read(&frag->frag_sem);
+
+	if (count < 0)
+		return count;
+	if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
+		return -EIO;
+	buffer->needs_read_fill = 0;
+	buffer->count = count;
+	return 0;
+}
+
+static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct configfs_buffer *buffer = file->private_data;
+	ssize_t retval = 0;
+
+	mutex_lock(&buffer->mutex);
+	if (buffer->needs_read_fill) {
+		retval = fill_read_buffer(file, buffer);
+		if (retval)
+			goto out;
+	}
+	pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
+		 __func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
+	if (iocb->ki_pos >= buffer->count)
+		goto out;
+	retval = copy_to_iter(buffer->page + iocb->ki_pos,
+			      buffer->count - iocb->ki_pos, to);
+	iocb->ki_pos += retval;
+	if (retval == 0)
+		retval = -EFAULT;
+out:
+	mutex_unlock(&buffer->mutex);
+	return retval;
+}
+
+static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct configfs_fragment *frag = to_frag(file);
+	struct configfs_buffer *buffer = file->private_data;
+	ssize_t retval = 0;
+	ssize_t len;
+
+	mutex_lock(&buffer->mutex);
+
+	/* we don't support switching read/write modes */
+	if (buffer->write_in_progress) {
+		retval = -ETXTBSY;
+		goto out;
+	}
+	buffer->read_in_progress = true;
+
+	if (buffer->needs_read_fill) {
+		/* perform first read with buf == NULL to get extent */
+		down_read(&frag->frag_sem);
+		if (!frag->frag_dead)
+			len = buffer->bin_attr->read(buffer->item, NULL, 0);
+		else
+			len = -ENOENT;
+		up_read(&frag->frag_sem);
+		if (len <= 0) {
+			retval = len;
+			goto out;
+		}
+
+		/* do not exceed the maximum value */
+		if (buffer->cb_max_size && len > buffer->cb_max_size) {
+			retval = -EFBIG;
+			goto out;
+		}
+
+		buffer->bin_buffer = vmalloc(len);
+		if (buffer->bin_buffer == NULL) {
+			retval = -ENOMEM;
+			goto out;
+		}
+		buffer->bin_buffer_size = len;
+
+		/* perform second read to fill buffer */
+		down_read(&frag->frag_sem);
+		if (!frag->frag_dead)
+			len = buffer->bin_attr->read(buffer->item,
+						     buffer->bin_buffer, len);
+		else
+			len = -ENOENT;
+		up_read(&frag->frag_sem);
+		if (len < 0) {
+			retval = len;
+			vfree(buffer->bin_buffer);
+			buffer->bin_buffer_size = 0;
+			buffer->bin_buffer = NULL;
+			goto out;
+		}
+
+		buffer->needs_read_fill = 0;
+	}
+
+	if (iocb->ki_pos >= buffer->bin_buffer_size)
+		goto out;
+	retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos,
+			      buffer->bin_buffer_size - iocb->ki_pos, to);
+	iocb->ki_pos += retval;
+	if (retval == 0)
+		retval = -EFAULT;
+out:
+	mutex_unlock(&buffer->mutex);
+	return retval;
+}
+
+/* Fill @buffer with data coming from @from. */
+static int fill_write_buffer(struct configfs_buffer *buffer,
+			     struct iov_iter *from)
+{
+	int copied;
+
+	if (!buffer->page)
+		buffer->page = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
+	buffer->needs_read_fill = 1;
+	/* if buf is assumed to contain a string, terminate it by \0,
+	 * so e.g. sscanf() can scan the string easily */
+	buffer->page[copied] = 0;
+	return copied ? : -EFAULT;
+}
+
+static int
+flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t count)
+{
+	struct configfs_fragment *frag = to_frag(file);
+	int res = -ENOENT;
+
+	down_read(&frag->frag_sem);
+	if (!frag->frag_dead)
+		res = buffer->attr->store(buffer->item, buffer->page, count);
+	up_read(&frag->frag_sem);
+	return res;
+}
+
+
+/*
+ * There is no easy way for us to know if userspace is only doing a partial
+ * write, so we don't support them. We expect the entire buffer to come on the
+ * first write.
+ * Hint: if you're writing a value, first read the file, modify only the value
+ * you're changing, then write entire buffer back.
+ */
+static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct configfs_buffer *buffer = file->private_data;
+	int len;
+
+	mutex_lock(&buffer->mutex);
+	len = fill_write_buffer(buffer, from);
+	if (len > 0)
+		len = flush_write_buffer(file, buffer, len);
+	if (len > 0)
+		iocb->ki_pos += len;
+	mutex_unlock(&buffer->mutex);
+	return len;
+}
+
+static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
+				       struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct configfs_buffer *buffer = file->private_data;
+	void *tbuf = NULL;
+	size_t end_offset;
+	ssize_t len;
+
+	mutex_lock(&buffer->mutex);
+
+	/* we don't support switching read/write modes */
+	if (buffer->read_in_progress) {
+		len = -ETXTBSY;
+		goto out;
+	}
+	buffer->write_in_progress = true;
+
+	/* buffer grows? */
+	end_offset = iocb->ki_pos + iov_iter_count(from);
+	if (end_offset > buffer->bin_buffer_size) {
+		if (buffer->cb_max_size && end_offset > buffer->cb_max_size) {
+			len = -EFBIG;
+			goto out;
+		}
+
+		tbuf = vmalloc(end_offset);
+		if (tbuf == NULL) {
+			len = -ENOMEM;
+			goto out;
+		}
+
+		/* copy old contents */
+		if (buffer->bin_buffer) {
+			memcpy(tbuf, buffer->bin_buffer,
+				buffer->bin_buffer_size);
+			vfree(buffer->bin_buffer);
+		}
+
+		/* clear the new area */
+		memset(tbuf + buffer->bin_buffer_size, 0,
+			end_offset - buffer->bin_buffer_size);
+		buffer->bin_buffer = tbuf;
+		buffer->bin_buffer_size = end_offset;
+	}
+
+	len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos,
+			     buffer->bin_buffer_size - iocb->ki_pos, from);
+	iocb->ki_pos += len;
+out:
+	mutex_unlock(&buffer->mutex);
+	return len ? : -EFAULT;
+}
+
+static int __configfs_open_file(struct inode *inode, struct file *file, int type)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct configfs_fragment *frag = to_frag(file);
+	struct configfs_attribute *attr;
+	struct configfs_buffer *buffer;
+	int error;
+
+	error = -ENOMEM;
+	buffer = kzalloc_obj(struct configfs_buffer);
+	if (!buffer)
+		goto out;
+
+	error = -ENOENT;
+	down_read(&frag->frag_sem);
+	if (unlikely(frag->frag_dead))
+		goto out_free_buffer;
+
+	error = -EINVAL;
+	buffer->item = to_item(dentry->d_parent);
+	if (!buffer->item)
+		goto out_free_buffer;
+
+	attr = to_attr(dentry);
+	if (!attr)
+		goto out_free_buffer;
+
+	if (type & CONFIGFS_ITEM_BIN_ATTR) {
+		buffer->bin_attr = to_bin_attr(dentry);
+		buffer->cb_max_size = buffer->bin_attr->cb_max_size;
+	} else {
+		buffer->attr = attr;
+	}
+
+	buffer->owner = attr->ca_owner;
+	/* Grab the module reference for this attribute if we have one */
+	error = -ENODEV;
+	if (!try_module_get(buffer->owner))
+		goto out_free_buffer;
+
+	error = -EACCES;
+	if (!buffer->item->ci_type)
+		goto out_put_module;
+
+	buffer->ops = buffer->item->ci_type->ct_item_ops;
+
+	/* File needs write support.
+	 * The inode's perms must say it's ok,
+	 * and we must have a store method.
+	 */
+	if (file->f_mode & FMODE_WRITE) {
+		if (!(inode->i_mode & S_IWUGO))
+			goto out_put_module;
+		if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
+			goto out_put_module;
+		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)
+			goto out_put_module;
+	}
+
+	/* File needs read support.
+	 * The inode's perms must say it's ok, and we there
+	 * must be a show method for it.
+	 */
+	if (file->f_mode & FMODE_READ) {
+		if (!(inode->i_mode & S_IRUGO))
+			goto out_put_module;
+		if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
+			goto out_put_module;
+		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)
+			goto out_put_module;
+	}
+
+	mutex_init(&buffer->mutex);
+	buffer->needs_read_fill = 1;
+	buffer->read_in_progress = false;
+	buffer->write_in_progress = false;
+	file->private_data = buffer;
+	up_read(&frag->frag_sem);
+	return 0;
+
+out_put_module:
+	module_put(buffer->owner);
+out_free_buffer:
+	up_read(&frag->frag_sem);
+	kfree(buffer);
+out:
+	return error;
+}
+
+static int configfs_release(struct inode *inode, struct file *filp)
+{
+	struct configfs_buffer *buffer = filp->private_data;
+
+	module_put(buffer->owner);
+	kfree(buffer->page);
+	mutex_destroy(&buffer->mutex);
+	kfree(buffer);
+	return 0;
+}
+
+static int configfs_open_file(struct inode *inode, struct file *filp)
+{
+	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);
+}
+
+static int configfs_open_bin_file(struct inode *inode, struct file *filp)
+{
+	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
+}
+
+static int configfs_release_bin_file(struct inode *inode, struct file *file)
+{
+	struct configfs_buffer *buffer = file->private_data;
+
+	if (buffer->write_in_progress) {
+		struct configfs_fragment *frag = to_frag(file);
+
+		down_read(&frag->frag_sem);
+		if (!frag->frag_dead) {
+			/* result of ->release() is ignored */
+			buffer->bin_attr->write(buffer->item,
+					buffer->bin_buffer,
+					buffer->bin_buffer_size);
+		}
+		up_read(&frag->frag_sem);
+	}
+
+	vfree(buffer->bin_buffer);
+
+	configfs_release(inode, file);
+	return 0;
+}
+
+
+const struct file_operations configfs_file_operations = {
+	.read_iter	= configfs_read_iter,
+	.write_iter	= configfs_write_iter,
+	.llseek		= generic_file_llseek,
+	.open		= configfs_open_file,
+	.release	= configfs_release,
+};
+
+const struct file_operations configfs_bin_file_operations = {
+	.read_iter	= configfs_bin_read_iter,
+	.write_iter	= configfs_bin_write_iter,
+	.llseek		= NULL,		/* bin file is not seekable */
+	.open		= configfs_open_bin_file,
+	.release	= configfs_release_bin_file,
+};
+
+/**
+ *	configfs_create_file - create an attribute file for an item.
+ *	@item:	item we're creating for.
+ *	@attr:	atrribute descriptor.
+ */
+
+int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
+{
+	struct dentry *dir = item->ci_dentry;
+	struct configfs_dirent *parent_sd = dir->d_fsdata;
+	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
+
+	inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
+	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
+				     CONFIGFS_ITEM_ATTR, parent_sd->s_frag);
+	inode_unlock(d_inode(dir));
+
+	return error;
+}
+
+/**
+ *	configfs_create_bin_file - create a binary attribute file for an item.
+ *	@item:	item we're creating for.
+ *	@bin_attr: atrribute descriptor.
+ */
+
+int configfs_create_bin_file(struct config_item *item,
+		const struct configfs_bin_attribute *bin_attr)
+{
+	struct dentry *dir = item->ci_dentry;
+	struct configfs_dirent *parent_sd = dir->d_fsdata;
+	umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
+
+	inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
+	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
+				     CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag);
+	inode_unlock(dir->d_inode);
+
+	return error;
+}