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

Masami Hiramatsu
2019-01-08T04:45:18Z

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
---
- 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