linux-kernel - [PATCH] ftrace: fix function type mismatches

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Message-Id: <20191007214740.188547-1-samitolvanen@google.com>
Date:   Mon,  7 Oct 2019 14:47:40 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH] ftrace: fix function type mismatches

This change fixes indirect call mismatches with function and function
graph tracing, which trip Control-Flow Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 kernel/trace/fgraph.c | 9 ++++++---
 kernel/trace/ftrace.c | 8 +++++---
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 7950a0356042..ecfd4a4a106a 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -327,14 +327,17 @@ void ftrace_graph_sleep_time_control(bool enable)
 	fgraph_sleep_time = enable;
 }
 
+void ftrace_graph_return_stub(struct ftrace_graph_ret *trace)
+{
+}
+
 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
 {
 	return 0;
 }
 
 /* The callbacks that hook a function */
-trace_func_graph_ret_t ftrace_graph_return =
-			(trace_func_graph_ret_t)ftrace_stub;
+trace_func_graph_ret_t ftrace_graph_return = ftrace_graph_return_stub;
 trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
 static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
 
@@ -614,7 +617,7 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
 		goto out;
 
 	ftrace_graph_active--;
-	ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
+	ftrace_graph_return = ftrace_graph_return_stub;
 	ftrace_graph_entry = ftrace_graph_entry_stub;
 	__ftrace_graph_entry = ftrace_graph_entry_stub;
 	ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 62a50bf399d6..b68ee130d4a2 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -125,8 +125,9 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 				 struct ftrace_ops *op, struct pt_regs *regs);
 #else
 /* See comment below, where ftrace_ops_list_func is defined */
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
-#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
+static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip,
+			      struct ftrace_ops *op, struct pt_regs *regs);
+#define ftrace_ops_list_func ftrace_ops_no_ops
 #endif
 
 static inline void ftrace_ops_init(struct ftrace_ops *ops)
@@ -6325,7 +6326,8 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 }
 NOKPROBE_SYMBOL(ftrace_ops_list_func);
 #else
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
+static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip,
+			      struct ftrace_ops *op, struct pt_regs *regs)
 {
 	__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
 }
-- 
2.23.0.581.g78d2f28ef7-goog