tracing: Have event inject files inc the trace array ref count

The event inject files add events for a specific trace array. For an
instance, if the file is opened and the instance is deleted, reading or
writing to the file will cause a use after free.

Up the ref count of the trace_array when a event inject file is opened.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/all/[email protected]/

Cc: [email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Zheng Yejian <[email protected]>
Fixes: 6c3edaf ("tracing: Introduce trace event injection")
Tested-by: Linux Kernel Functional Testing <[email protected]>
Tested-by: Naresh Kamboju <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: rostedt

kernel/trace/trace_events_inject.c

@@ -328,7 +328,8 @@ event_inject_read(struct file *file, char __user *buf, size_t size,
 }
 
 const struct file_operations event_inject_fops = {
-	.open = tracing_open_generic,
+	.open = tracing_open_file_tr,
 	.read = event_inject_read,
 	.write = event_inject_write,
+	.release = tracing_release_file_tr,
 };