[PATCH v2 1/4] trace-cmd: Fix trace-cmd report crash while displaying trace.dat in specific use case

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

The trace-cmd report command crashes while displaying a file recorded with "--proc-map" and "-B" options:
#trace-cmd record --proc-map  -B test -e sched -F sleep 1
The "--proc-map" options saves the address map of "sleep" into the trace.dat file. This
information is used by KernelShark. The "-B" options traces the specified events into a
ftrace instance "test".
When such file is opened using libtracecmd APIs, the proc-map is parsed and saved into
a tracecmd_input handler, as linked list "pid_maps". Later, when the ftrace instance
"test" is parsed, a copy of this handler is used to fill it with the instance's trace data.
Both tracecmd_input handlers share the same "pid_maps" list, thus leads to a double
free of the list, when  handlers are destroyed.
As this "pid_maps" is not used in ftrace buffers, the "pid_maps" list of the copy can be
initialized to NULL.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 55c3d80a..7583d5cb 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -3712,6 +3712,8 @@ tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx)
 
 	new_handle->flags |= TRACECMD_FL_BUFFER_INSTANCE;
 
+	new_handle->pid_maps = NULL;
+
 	/* Save where we currently are */
 	offset = lseek64(handle->fd, 0, SEEK_CUR);
 
-- 
2.26.2