[PATCH 2/3] tracing: Adding additional NULL checks.

[Divya Indi <divya.indi@oracle.com>]

commit f45d1225adb0 ("tracing: Kernel access to Ftrace instances")
exported certain functions providing access to Ftrace instances from
other kernel components.
Adding some additional NULL checks to ensure safe usage by the users.

Signed-off-by: Divya Indi <divya.indi@oracle.com>
---
 kernel/trace/trace.c        | 3 +++
 kernel/trace/trace_events.c | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1c80521..a60dc13 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3205,6 +3205,9 @@ int trace_array_printk(struct trace_array *tr,
 	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
 		return 0;
 
+	if (!tr)
+		return -EINVAL;
+
 	va_start(ap, fmt);
 	ret = trace_array_vprintk(tr, ip, fmt, ap);
 	va_end(ap);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b6b4618..445b059 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -800,6 +800,8 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
 	char *event = NULL, *sub = NULL, *match;
 	int ret;
 
+	if (!tr)
+		return -ENODEV;
 	/*
 	 * The buf format can be <subsystem>:<event-name>
 	 *  *:<event-name> means any event by that name.
-- 
1.8.3.1