--- /dev/null
+From c93f5cf571e7795f97d49ef51b766cf25e328545 Mon Sep 17 00:00:00 2001
+From: Masami Hiramatsu <mhiramat@kernel.org>
+Date: Thu, 25 May 2017 19:38:17 +0900
+Subject: kprobes/x86: Fix to set RWX bits correctly before releasing trampoline
+
+From: Masami Hiramatsu <mhiramat@kernel.org>
+
+commit c93f5cf571e7795f97d49ef51b766cf25e328545 upstream.
+
+Fix kprobes to set(recover) RWX bits correctly on trampoline
+buffer before releasing it. Releasing readonly page to
+module_memfree() crash the kernel.
+
+Without this fix, if kprobes user register a bunch of kprobes
+in function body (since kprobes on function entry usually
+use ftrace) and unregister it, kernel hits a BUG and crash.
+
+Link: http://lkml.kernel.org/r/149570868652.3518.14120169373590420503.stgit@devbox
+
+Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
+Fixes: d0381c81c2f7 ("kprobes/x86: Set kprobes pages read-only")
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/kernel/kprobes/core.c | 9 +++++++++
+ kernel/kprobes.c | 2 +-
+ 2 files changed, 10 insertions(+), 1 deletion(-)
+
+--- a/arch/x86/kernel/kprobes/core.c
++++ b/arch/x86/kernel/kprobes/core.c
+@@ -51,6 +51,7 @@
+ #include <linux/ftrace.h>
+ #include <linux/frame.h>
+ #include <linux/kasan.h>
++#include <linux/moduleloader.h>
+
+ #include <asm/text-patching.h>
+ #include <asm/cacheflush.h>
+@@ -405,6 +406,14 @@ int __copy_instruction(u8 *dest, u8 *src
+ return length;
+ }
+
++/* Recover page to RW mode before releasing it */
++void free_insn_page(void *page)
++{
++ set_memory_nx((unsigned long)page & PAGE_MASK, 1);
++ set_memory_rw((unsigned long)page & PAGE_MASK, 1);
++ module_memfree(page);
++}
++
+ static int arch_copy_kprobe(struct kprobe *p)
+ {
+ int ret;
+--- a/kernel/kprobes.c
++++ b/kernel/kprobes.c
+@@ -125,7 +125,7 @@ static void *alloc_insn_page(void)
+ return module_alloc(PAGE_SIZE);
+ }
+
+-static void free_insn_page(void *page)
++void __weak free_insn_page(void *page)
+ {
+ module_memfree(page);
+ }