From 84047e360af0394ac5861d433f26bbcf30f77dd1 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 2 Jun 2009 16:51:55 -0400 Subject: function-graph: always initialize task ret_stack On creating a new task while running the function graph tracer, if we fail to allocate the ret_stack, and then fail the fork, the code will free the parent ret_stack. This is because the child duplicated the parent and currently points to the parent's ret_stack. This patch always initializes the task's ret_stack to NULL. [ Impact: prevent crash of parent on low memory during fork ] Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1664d3f33d3..bb081f37cac 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2738,6 +2738,9 @@ void unregister_ftrace_graph(void) /* Allocate a return stack for newly created task */ void ftrace_graph_init_task(struct task_struct *t) { + /* Make sure we do not use the parent ret_stack */ + t->ret_stack = NULL; + if (atomic_read(&ftrace_graph_active)) { struct ftrace_ret_stack *ret_stack; @@ -2753,8 +2756,7 @@ void ftrace_graph_init_task(struct task_struct *t) /* make curr_ret_stack visable before we add the ret_stack */ smp_wmb(); t->ret_stack = ret_stack; - } else - t->ret_stack = NULL; + } } void ftrace_graph_exit_task(struct task_struct *t) -- cgit v1.2.3-70-g09d2