tracing: Don't make assumptions about length of string on task rename

While the dest comm string size is assured to be at least TASK_COMM_LEN long,
doing a memcpy() also adds the assumption that the source is at least that
long as well, which isn't assured, and isn't true in cases such as:

	set_task_comm(worker->task, "kworker/dying");

This leads to accessing invalid memory.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

diff --git a/include/trace/events/task.h b/include/trace/events/task.h
index dee3bb1d5a6b5b28d001b98f46ea9694d7a6bb65..2cca6cd342d897f90269cf1542df40d4a1858a18 100644 (file)
--- a/include/trace/events/task.h
+++ b/include/trace/events/task.h
@@ -46,7 +46,7 @@ TRACE_EVENT(task_rename,
        TP_fast_assign(
                __entry->pid = task->pid;
                memcpy(entry->oldcomm, task->comm, TASK_COMM_LEN);
-               memcpy(entry->newcomm, comm, TASK_COMM_LEN);
+               strlcpy(entry->newcomm, comm, TASK_COMM_LEN);
                __entry->oom_score_adj = task->signal->oom_score_adj;
        ),