[PATCH 4.4 63/92] ARM: 8771/1: kprobes: Prohibit kprobes on do_undefinstr

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

commit eb0146daefdde65665b7f076fbff7b49dade95b9 upstream.

Prohibit kprobes on do_undefinstr because kprobes on
arm is implemented by undefined instruction. This means
if we probe do_undefinstr(), it can cause infinit
recursive exception.

Fixes: 24ba613c9d6c ("ARM kprobes: core code")
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/arm/kernel/traps.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -19,6 +19,7 @@
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
 #include <linux/kdebug.h>
+#include <linux/kprobes.h>
 #include <linux/module.h>
 #include <linux/kexec.h>
 #include <linux/bug.h>
@@ -395,7 +396,8 @@ void unregister_undef_hook(struct undef_
 	raw_spin_unlock_irqrestore(&undef_lock, flags);
 }
 
-static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
+static nokprobe_inline
+int call_undef_hook(struct pt_regs *regs, unsigned int instr)
 {
 	struct undef_hook *hook;
 	unsigned long flags;
@@ -468,6 +470,7 @@ die_sig:
 
 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
 }
+NOKPROBE_SYMBOL(do_undefinstr)
 
 /*
  * Handle FIQ similarly to NMI on x86 systems.