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 <[e-mail]>
Cc: David Daney <[e-mail]>
Cc: Maneesh Soni <[e-mail]>
Cc: Victor Kamensky <[e-mail]>
Cc: [e-mail]
Cc: Ingo Molnar <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/5293/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/kernel/kprobes.c

···
 
 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)