[PATCH v2 2/4] arm64: unwind: Prohibit probing on return_address()

Masami Hiramatsu
2019-07-22T07:49:15Z

Prohibit probing on return_address() and subroutines which
is called from return_address(), since the it is invoked from
trace_hardirqs_off() which is also kprobe blacklisted.

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
arch/arm64/kernel/return_address.c | 4 +++-
arch/arm64/kernel/stacktrace.c | 3 +++
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c
index b21cba90f82d..7f8a143268b0 100644
--- a/arch/arm64/kernel/return_address.c
+++ b/arch/arm64/kernel/return_address.c
@@ -8,6 +8,7 @@

#include <linux/export.h>
#include <linux/ftrace.h>
+#include <linux/kprobes.h>

#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
@@ -17,7 +18,7 @@ struct return_address_data {
void *addr;
};

-static int save_return_addr(struct stackframe *frame, void *d)
+static nokprobe_inline int save_return_addr(struct stackframe *frame, void *d)
{
struct return_address_data *data = d;

@@ -52,3 +53,4 @@ void *return_address(unsigned int level)
return NULL;
}
EXPORT_SYMBOL_GPL(return_address);
+NOKPROBE_SYMBOL(return_address);
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 62d395151abe..cd7dab54d17b 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -7,6 +7,7 @@
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/ftrace.h>
+#include <linux/kprobes.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
@@ -73,6 +74,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)

return 0;
}
+NOKPROBE_SYMBOL(unwind_frame);

void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
int (*fn)(struct stackframe *, void *), void *data)
@@ -87,6 +89,7 @@ void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
break;
}
}
+NOKPROBE_SYMBOL(walk_stackframe);

#ifdef CONFIG_STACKTRACE
struct stack_trace_data {