kprobes/x86: Free 'optinsn' cache when range check fails

This patch frees the 'optinsn' slot when we get a range check error,
to prevent memory leaks.

Before this patch, cache entry in kprobe_insn_cache() won't be freed
if kprobe optimizing fails due to range check failure.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Pei Feiyue <peifeiyue@huawei.com>
Link: http://lkml.kernel.org/r/1406550019-70935-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/kprobes/opt.c

@@ -338,8 +338,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
 	 * a relative jump.
 	 */
 	rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
-	if (abs(rel) > 0x7fffffff)
+	if (abs(rel) > 0x7fffffff) {
+		__arch_remove_optimized_kprobe(op, 0);
 		return -ERANGE;
+	}
 
 	buf = (u8 *)op->optinsn.insn;