| Date | Tue, 30 Mar 2010 15:40:54 -0700 | From | Greg KH <> | Subject | [020/156] function-graph: Init curr_ret_stack with ret_stack |
| |
2.6.33-stable review patch. If anyone has any objections, please let us know.
------------------
From: Steven Rostedt <srostedt@redhat.com>
commit ea14eb714041d40fcc5180b5a586034503650149 upstream.
If the graph tracer is active, and a task is forked but the allocating of the processes graph stack fails, it can cause crash later on.
This is due to the temporary stack being NULL, but the curr_ret_stack variable is copied from the parent. If it is not -1, then in ftrace_graph_probe_sched_switch() the following:
for (index = next->curr_ret_stack; index >= 0; index--) next->ret_stack[index].calltime += timestamp;
Will cause a kernel OOPS.
Found with Li Zefan's ftrace_stress_test.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/trace/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3364,6 +3364,7 @@ void ftrace_graph_init_task(struct task_ { /* Make sure we do not use the parent ret_stack */ t->ret_stack = NULL; + t->curr_ret_stack = -1; if (ftrace_graph_active) { struct ftrace_ret_stack *ret_stack; @@ -3373,7 +3374,6 @@ void ftrace_graph_init_task(struct task_ GFP_KERNEL); if (!ret_stack) return; - t->curr_ret_stack = -1; atomic_set(&t->tracing_graph_pause, 0); atomic_set(&t->trace_overrun, 0); t->ftrace_timestamp = 0;
|