Re: [PATCH v2 2/3] kprobes: Mark ftrace mcount handler functions nokprobe

Steven Rostedt
2019-01-09T14:31:25Z

On Tue, 8 Jan 2019 13:44:54 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Mark ftrace mcount handler functions nokprobe since
> probing on these functions with kretprobe pushes
> return address incorrectly on kretprobe shadow stack.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com>
> Tested-by: Andrea Righi <righi.andrea@gmail.com>
> Cc: stable@vger.kernel.org

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> ---
> - Changes in v2:
> Fix to include kprobes.h (Thanks Andrea!)
> ---
> kernel/trace/ftrace.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index f0ff24173a0b..b0774388d52b 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -34,6 +34,7 @@
> #include <linux/list.h>
> #include <linux/hash.h>
> #include <linux/rcupdate.h>
> +#include <linux/kprobes.h>
>
> #include <trace/events/sched.h>
>
> @@ -6250,7 +6251,7 @@ void ftrace_reset_array_ops(struct trace_array *tr)
> tr->ops->func = ftrace_stub;
> }
>
> -static inline void
> +static nokprobe_inline void
> __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *ignored, struct pt_regs *regs)
> {
> @@ -6310,11 +6311,13 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, regs);
> }
> +NOKPROBE_SYMBOL(ftrace_ops_list_func);
> #else
> static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
> }
> +NOKPROBE_SYMBOL(ftrace_ops_no_ops);
> #endif
>
> /*
> @@ -6341,6 +6344,7 @@ static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
> preempt_enable_notrace();
> trace_clear_recursion(bit);
> }
> +NOKPROBE_SYMBOL(ftrace_ops_assist_func);
>
> /**
> * ftrace_ops_get_func - get the function a trampoline should call