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Commit a6c9fb2c authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware) Committed by Greg Kroah-Hartman
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ftrace: Get a reference counter for the trace_array on filter files 



commit 9ef16693aff8137faa21d16ffe65bb9832d24d71 upstream.

The ftrace set_ftrace_filter and set_ftrace_notrace files are specific for
an instance now. They need to take a reference to the instance otherwise
there could be a race between accessing the files and deleting the instance.

It wasn't until the :mod: caching where these file operations started
referencing the trace_array directly.

Cc: stable@vger.kernel.org
Fixes: 673feb9d ("ftrace: Add :mod: caching infrastructure to trace_array")
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b7f75863

kernel/trace/ftrace.c

+18 −9
Original line number Diff line number Diff line
@@ -3557,21 +3557,22 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag, 
	struct ftrace_hash *hash;

	struct list_head *mod_head;

	struct trace_array *tr = ops->private;

	int ret = 0;

	int ret = -ENOMEM;



	ftrace_ops_init(ops);



	if (unlikely(ftrace_disabled))

		return -ENODEV;



	if (tr && trace_array_get(tr) < 0)

		return -ENODEV;



	iter = kzalloc(sizeof(*iter), GFP_KERNEL);

	if (!iter)

		return -ENOMEM;

		goto out;



	if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX)) {

		kfree(iter);

		return -ENOMEM;

	}

	if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX))

		goto out;



	iter->ops = ops;

	iter->flags = flag;
@@ -3601,13 +3602,13 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag, 


		if (!iter->hash) {

			trace_parser_put(&iter->parser);

			kfree(iter);

			ret = -ENOMEM;

			goto out_unlock;

		}

	} else

		iter->hash = hash;



	ret = 0;



	if (file->f_mode & FMODE_READ) {

		iter->pg = ftrace_pages_start;
@@ -3619,7 +3620,6 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag, 
			/* Failed */

			free_ftrace_hash(iter->hash);

			trace_parser_put(&iter->parser);

			kfree(iter);

		}

	} else

		file->private_data = iter;
@@ -3627,6 +3627,13 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag, 
 out_unlock:

	mutex_unlock(&ops->func_hash->regex_lock);



 out:

	if (ret) {

		kfree(iter);

		if (tr)

			trace_array_put(tr);

	}



	return ret;

}
@@ -5024,6 +5031,8 @@ int ftrace_regex_release(struct inode *inode, struct file *file) 


	mutex_unlock(&iter->ops->func_hash->regex_lock);

	free_ftrace_hash(iter->hash);

	if (iter->tr)

		trace_array_put(iter->tr);

	kfree(iter);



	return 0;