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Commit b3435cd9 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Greg Kroah-Hartman
Browse files

tracing/probes: Reject events which have the same name of existing one 

[ Upstream commit 8e242060c6a4947e8ae7d29794af6a581db08841 ]

Since kprobe_events and uprobe_events only check whether the
other same-type probe event has the same name or not, if the
user gives the same name of the existing tracepoint event (or
the other type of probe events), it silently fails to create
the tracefs entry (but registered.) as below.

/sys/kernel/tracing # ls events/task/task_rename
enable   filter   format   hist     id       trigger
/sys/kernel/tracing # echo p:task/task_rename vfs_read >> kprobe_events
[  113.048508] Could not create tracefs 'task_rename' directory
/sys/kernel/tracing # cat kprobe_events
p:task/task_rename vfs_read

To fix this issue, check whether the existing events have the
same name or not in trace_probe_register_event_call(). If exists,
it rejects to register the new event.

Link: https://lkml.kernel.org/r/162936876189.187130.17558311387542061930.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 32280649

kernel/trace/trace_kprobe.c

+5 −1
Original line number Diff line number Diff line
@@ -646,6 +646,10 @@ static int register_trace_kprobe(struct trace_kprobe *tk) 
	/* Register new event */

	ret = register_kprobe_event(tk);

	if (ret) {

		if (ret == -EEXIST) {

			trace_probe_log_set_index(0);

			trace_probe_log_err(0, EVENT_EXIST);

		} else

			pr_warn("Failed to register probe event(%d)\n", ret);

		goto end;

	}

kernel/trace/trace_probe.c

+25 −0
Original line number Diff line number Diff line
@@ -1029,11 +1029,36 @@ int trace_probe_init(struct trace_probe *tp, const char *event, 
	return ret;

}



static struct trace_event_call *

find_trace_event_call(const char *system, const char *event_name)

{

	struct trace_event_call *tp_event;

	const char *name;



	list_for_each_entry(tp_event, &ftrace_events, list) {

		if (!tp_event->class->system ||

		    strcmp(system, tp_event->class->system))

			continue;

		name = trace_event_name(tp_event);

		if (!name || strcmp(event_name, name))

			continue;

		return tp_event;

	}



	return NULL;

}



int trace_probe_register_event_call(struct trace_probe *tp)

{

	struct trace_event_call *call = trace_probe_event_call(tp);

	int ret;



	lockdep_assert_held(&event_mutex);



	if (find_trace_event_call(trace_probe_group_name(tp),

				  trace_probe_name(tp)))

		return -EEXIST;



	ret = register_trace_event(&call->event);

	if (!ret)

		return -ENODEV;

kernel/trace/trace_probe.h

+1 −0
Original line number Diff line number Diff line
@@ -410,6 +410,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, 
	C(NO_EVENT_NAME,	"Event name is not specified"),		\

	C(EVENT_TOO_LONG,	"Event name is too long"),		\

	C(BAD_EVENT_NAME,	"Event name must follow the same rules as C identifiers"), \

	C(EVENT_EXIST,		"Given group/event name is already used by another event"), \

	C(RETVAL_ON_PROBE,	"$retval is not available on probe"),	\

	C(BAD_STACK_NUM,	"Invalid stack number"),		\

	C(BAD_ARG_NUM,		"Invalid argument number"),		\

kernel/trace/trace_uprobe.c

+5 −1
Original line number Diff line number Diff line
@@ -514,6 +514,10 @@ static int register_trace_uprobe(struct trace_uprobe *tu) 


	ret = register_uprobe_event(tu);

	if (ret) {

		if (ret == -EEXIST) {

			trace_probe_log_set_index(0);

			trace_probe_log_err(0, EVENT_EXIST);

		} else

			pr_warn("Failed to register probe event(%d)\n", ret);

		goto end;

	}