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Commit b9040fab authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware) Committed by Greg Kroah-Hartman
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tracing: Get trace_array reference for available_tracers files 



commit 194c2c74f5532e62c218adeb8e2b683119503907 upstream.

As instances may have different tracers available, we need to look at the
trace_array descriptor that shows the list of the available tracers for the
instance. But there's a race between opening the file and an admin
deleting the instance. The trace_array_get() needs to be called before
accessing the trace_array.

Cc: stable@vger.kernel.org
Fixes: 607e2ea1 ("tracing: Set up infrastructure to allow tracers for instances")
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a6c9fb2c

kernel/trace/trace.c

+15 −2
Original line number Original line Diff line number Diff line
@@ -4154,9 +4154,14 @@ static int show_traces_open(struct inode *inode, struct file *file) 
	if (tracing_disabled)

	if (tracing_disabled)

		return -ENODEV;

		return -ENODEV;





	if (trace_array_get(tr) < 0)

		return -ENODEV;



	ret = seq_open(file, &show_traces_seq_ops);

	ret = seq_open(file, &show_traces_seq_ops);

	if (ret)

	if (ret) {

		trace_array_put(tr);

		return ret;

		return ret;

	}





	m = file->private_data;

	m = file->private_data;

	m->private = tr;

	m->private = tr;
@@ -4164,6 +4169,14 @@ static int show_traces_open(struct inode *inode, struct file *file) 
	return 0;

	return 0;

}

}





static int show_traces_release(struct inode *inode, struct file *file)

{

	struct trace_array *tr = inode->i_private;



	trace_array_put(tr);

	return seq_release(inode, file);

}



static ssize_t

static ssize_t

tracing_write_stub(struct file *filp, const char __user *ubuf,

tracing_write_stub(struct file *filp, const char __user *ubuf,

		   size_t count, loff_t *ppos)

		   size_t count, loff_t *ppos)
@@ -4194,8 +4207,8 @@ static const struct file_operations tracing_fops = { 
static const struct file_operations show_traces_fops = {

static const struct file_operations show_traces_fops = {

	.open		= show_traces_open,

	.open		= show_traces_open,

	.read		= seq_read,

	.read		= seq_read,

	.release	= seq_release,

	.llseek		= seq_lseek,

	.llseek		= seq_lseek,

	.release	= show_traces_release,

};

};





static ssize_t

static ssize_t