From: Steven Rostedt Date: Sat, 13 Mar 2010 00:41:23 +0000 (-0500) Subject: function-graph: Init curr_ret_stack with ret_stack X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ea14eb714041d40fcc5180b5a586034503650149;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git function-graph: Init curr_ret_stack with ret_stack 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. Cc: stable@kernel.org Signed-off-by: Steven Rostedt --- diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d4d1238b096b..bb53edbb5c8c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3349,6 +3349,7 @@ void ftrace_graph_init_task(struct task_struct *t) { /* 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; @@ -3358,7 +3359,6 @@ void ftrace_graph_init_task(struct task_struct *t) 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;