releases/4.4.133/arm-8771-1-kprobes-prohibit-kprobes-on-do_undefinstr.patch

   1 From eb0146daefdde65665b7f076fbff7b49dade95b9 Mon Sep 17 00:00:00 2001
   2 From: Masami Hiramatsu <mhiramat@kernel.org>
   3 Date: Sun, 13 May 2018 05:04:16 +0100
   4 Subject: ARM: 8771/1: kprobes: Prohibit kprobes on do_undefinstr
   5
   6 From: Masami Hiramatsu <mhiramat@kernel.org>
   7
   8 commit eb0146daefdde65665b7f076fbff7b49dade95b9 upstream.
   9
  10 Prohibit kprobes on do_undefinstr because kprobes on
  11 arm is implemented by undefined instruction. This means
  12 if we probe do_undefinstr(), it can cause infinit
  13 recursive exception.
  14
  15 Fixes: 24ba613c9d6c ("ARM kprobes: core code")
  16 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
  17 Cc: stable@vger.kernel.org
  18 Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  arch/arm/kernel/traps.c |    5 ++++-
  23  1 file changed, 4 insertions(+), 1 deletion(-)
  24
  25 --- a/arch/arm/kernel/traps.c
  26 +++ b/arch/arm/kernel/traps.c
  27 @@ -19,6 +19,7 @@
  28  #include <linux/uaccess.h>
  29  #include <linux/hardirq.h>
  30  #include <linux/kdebug.h>
  31 +#include <linux/kprobes.h>
  32  #include <linux/module.h>
  33  #include <linux/kexec.h>
  34  #include <linux/bug.h>
  35 @@ -395,7 +396,8 @@ void unregister_undef_hook(struct undef_
  36         raw_spin_unlock_irqrestore(&undef_lock, flags);
  37  }
  38
  39 -static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
  40 +static nokprobe_inline
  41 +int call_undef_hook(struct pt_regs *regs, unsigned int instr)
  42  {
  43         struct undef_hook *hook;
  44         unsigned long flags;
  45 @@ -468,6 +470,7 @@ die_sig:
  46
  47         arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
  48  }
  49 +NOKPROBE_SYMBOL(do_undefinstr)
  50
  51  /*
  52   * Handle FIQ similarly to NMI on x86 systems.