kprobes/mips: Fix to check double free of insn slot

Fix to check double free of insn_slot at arch_remove_kprobe
as other arches do.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Maneesh Soni <manesoni@cisco.com>
Cc: Victor Kamensky <kamensky@cisco.com>
Cc: linux-mips@linux-mips.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: yrl.pp-manager.tt@hitachi.com
Cc: systemtap@sourceware.org
Patchwork: https://patchwork.linux-mips.org/patch/5293/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 12bc4ebdf55b..1f8187ab0997 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -207,7 +207,10 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-        free_insn_slot(p->ainsn.insn, 0);
+        if (p->ainsn.insn) {
+                free_insn_slot(p->ainsn.insn, 0);
+                p->ainsn.insn = NULL;
+        }
 }
 
 static void save_previous_kprobe(struct kprobe_ctlblk *kcb)