Merge tag 'trace-fixes-v3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "This includes two fixes.

  1) is a bug fix that happens when root does the following:

     echo function_graph > current_tracer
     modprobe foo
     echo nop > current_tracer

   This causes the ftrace internal accounting to get screwed up and
   crashes ftrace, preventing the user from using the function tracer
   after that.

  2) if a TRACE_EVENT has a string field, and NULL is given for it.

   The internal trace event code does a strlen() and strcpy() on the
   source of field.  If it is NULL it causes the system to oops.

   This bug has been there since 2.6.31, but no TRACE_EVENT ever passed
   in a NULL to the string field, until now"

* tag 'trace-fixes-v3.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace: Fix function graph with loading of modules
  tracing: Allow events to have NULL strings

1 files changed, 3 insertions, 2 deletions

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 52594b20179e..d17a35c6537e 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -372,7 +372,8 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call)	\
         __data_size += (len) * sizeof(type);
 
 #undef __string
-#define __string(item, src) __dynamic_array(char, item, strlen(src) + 1)
+#define __string(item, src) __dynamic_array(char, item,                 \
+                    strlen((src) ? (const char *)(src) : "(null)") + 1)
 
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)  \
@@ -501,7 +502,7 @@ static inline notrace int ftrace_get_offsets_##call(			\
 
 #undef __assign_str
 #define __assign_str(dst, src)                                          \
-        strcpy(__get_str(dst), src);
+        strcpy(__get_str(dst), (src) ? (const char *)(src) : "(null)");
 
 #undef TP_fast_assign
 #define TP_fast_assign(args...) args