Commit ba470eeb authored by sunliming's avatar sunliming Committed by Steven Rostedt (Google)
Browse files

tracing/user_events: Prevent same name but different args event 

User processes register name_args for events. If the same name but different
args event are registered. The trace outputs of second event are printed
as the first event. This is incorrect.

Return EADDRINUSE back to the user process if the same name but different args
event has being registered.

Link: https://lore.kernel.org/linux-trace-kernel/20230529032100.286534-1-sunliming@kylinos.cn



Signed-off-by: default avatarsunliming <sunliming@kylinos.cn>
Reviewed-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarBeau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent aafbb1ee

kernel/trace/trace_events_user.c

+30 −6
Original line number Diff line number Diff line
@@ -1786,6 +1786,8 @@ static int user_event_parse(struct user_event_group *group, char *name, 
	int ret;

	u32 key;

	struct user_event *user;

	int argc = 0;

	char **argv;



	/* Prevent dyn_event from racing */

	mutex_lock(&event_mutex);
@@ -1793,13 +1795,35 @@ static int user_event_parse(struct user_event_group *group, char *name, 
	mutex_unlock(&event_mutex);



	if (user) {

		if (args) {

			argv = argv_split(GFP_KERNEL, args, &argc);

			if (!argv) {

				ret = -ENOMEM;

				goto error;

			}



			ret = user_fields_match(user, argc, (const char **)argv);

			argv_free(argv);



		} else

			ret = list_empty(&user->fields);



		if (ret) {

			*newuser = user;

			/*

			 * Name is allocated by caller, free it since it already exists.

			 * Caller only worries about failure cases for freeing.

			 */

			kfree(name);

		} else {

			ret = -EADDRINUSE;

			goto error;

		}



		return 0;

error:

		refcount_dec(&user->refcnt);

		return ret;

	}



	user = kzalloc(sizeof(*user), GFP_KERNEL_ACCOUNT);

tools/testing/selftests/user_events/ftrace_test.c

+6 −0
Original line number Diff line number Diff line
@@ -228,6 +228,12 @@ TEST_F(user, register_events) { 
	ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));

	ASSERT_EQ(0, reg.write_index);



	/* Multiple registers to same name but different args should fail */

	reg.enable_bit = 29;

	reg.name_args = (__u64)"__test_event u32 field1;";

	ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSREG, &reg));

	ASSERT_EQ(EADDRINUSE, errno);



	/* Ensure disabled */

	self->enable_fd = open(enable_file, O_RDWR);

	ASSERT_NE(-1, self->enable_fd);