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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Russell King <linux@armlinux.org.uk>
Cc:     Wang Nan <wangnan0@huawei.com>, Will Deacon <will.deacon@arm.com>,
        Jon Medhurst <tixy@linaro.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        mhiramat@kernel.org, David Long <dave.long@linaro.org>,
        stable@vger.kernel.org
Subject: [BUGFIX PATCH v3 3/4] arm: kprobes: Prohibit kprobes on do_undefinstr
Date:   Fri,  4 May 2018 13:15:58 +0900
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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@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm/kernel/traps.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 5e3633c24e63..2fe87109ae46 100644
--- 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>
@@ -417,7 +418,8 @@ void unregister_undef_hook(struct undef_hook *hook)
 	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;
@@ -490,6 +492,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
 
 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
 }
+NOKPROBE_SYMBOL(do_undefinstr)
 
 /*
  * Handle FIQ similarly to NMI on x86 systems.