commit 9a77c36c4a5ed7d218d3a5d154ef73e430e50052
author Sami Tolvanen <samitolvanen@google.com> Thu May 10 14:56:41 2018 -0700
committer SamarV-121 <samarvispute121@pm.me> Sun Nov 06 10:12:10 2022 +0530
tree bb35977da640ddf2e6ae6a0a233bf53d0a818e8e
parent 7306266e0a502ce70abb9ec37c6e8fc4ebd2748f

BACKPORT: ANDROID: ftrace: fix function type mismatches

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

Bug: 79510107
Bug: 67506682
Change-Id: I5de08c113fb970ffefedce93c58e0161f22c7ca2
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
(cherry picked from commit c2f9bce9fee8e31e0500c501076f73db7791d8e9)
Signed-off-by: Dan Aloni <daloni@magicleap.com>
Signed-off-by: Davide Garberi <dade.garberi@gmail.com>

include/linux/ftrace.h

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 312a4ef..7bff40e 100755
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -244,8 +244,16 @@
 	return *this_cpu_ptr(ops->disabled);
 }
 
+#ifdef CONFIG_CFI_CLANG
+/* Use a C stub with the correct type for CFI */
+static inline void ftrace_stub(unsigned long a0, unsigned long a1,
+			       struct ftrace_ops *op, struct pt_regs *regs)
+{
+}
+#else
 extern void ftrace_stub(unsigned long a0, unsigned long a1,
 			struct ftrace_ops *op, struct pt_regs *regs);
+#endif
 
 #else /* !CONFIG_FUNCTION_TRACER */
 /*

kernel/trace/ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d90b42b..40cba7f 100755
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -127,8 +127,9 @@
 				 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
 
 /*
@@ -5215,7 +5216,8 @@
 	__ftrace_ops_list_func(ip, parent_ip, NULL, regs);
 }
 #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);
 }
@@ -5661,14 +5663,17 @@
 	fgraph_graph_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;
 
@@ -5897,7 +5902,7 @@
 		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);