[PATCH -tip v3 20/23] [BUGFIX] kprobes: Prohibit probing on func_ptr_is_kernel_text

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

Prohibit probing on func_ptr_is_kernel_text() by adding
it to the kprobe_blacklist.

Since the func_ptr_is_kernel_text() is called from
notifier_call_chain() which is called from int3 handler,
probing it may cause double int3 fault and kernel will
reboot.

This happenes when the kernel built with CONFIG_DEBUG_NOTIFIERS=y.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@kernel.org>
---
 kernel/extable.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/extable.c b/kernel/extable.c
index 832cb28..885c877 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/init.h>
+#include <linux/kprobes.h>
 
 #include <asm/sections.h>
 #include <asm/uaccess.h>
@@ -137,3 +138,4 @@ int func_ptr_is_kernel_text(void *ptr)
 		return 1;
 	return is_module_text_address(addr);
 }
+NOKPROBE_SYMBOL(func_ptr_is_kernel_text);