linux-kernel - [PATCH 4.9 27/87] ARM: 8771/1: kprobes: Prohibit kprobes on do

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Message-Id: <20180521210422.874003888@linuxfoundation.org>
Date:   Mon, 21 May 2018 23:11:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Masami Hiramatsu <mhiramat@...nel.org>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH 4.9 27/87] ARM: 8771/1: kprobes: Prohibit kprobes on do_undefinstr

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

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

From: Masami Hiramatsu <mhiramat@...nel.org>

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@...nel.org>
Cc: stable@...r.kernel.org
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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>
@@ -415,7 +416,8 @@ 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;
@@ -488,6 +490,7 @@ die_sig:
 
 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
 }
+NOKPROBE_SYMBOL(do_undefinstr)
 
 /*
  * Handle FIQ similarly to NMI on x86 systems.