From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761171AbbA1CRU (ORCPT ); Tue, 27 Jan 2015 21:17:20 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:18427 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761153AbbA1CRQ (ORCPT ); Tue, 27 Jan 2015 21:17:16 -0500 From: Boris Ostrovsky To: bp@alien8.de Cc: x86@kernel.org, linux-kernel@vger.kernel.org, james@dingwall.me.uk, boris.ostrovsky@oracle.com, stable@vger.kernel.org.#.3.18 Subject: [PATCH] x86, microcode: Return error from driver init code when loader is disabled Date: Tue, 27 Jan 2015 21:21:09 -0500 Message-Id: <1422411669-25147-1-git-send-email-boris.ostrovsky@oracle.com> X-Mailer: git-send-email 1.9.3 X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commits 65cef1311d5d ("x86, microcode: Add a disable chicken bit") and a18a0f6850d4 ("x86, microcode: Don't initialize microcode code on paravirt") allow microcode driver skip initialization when microcode loading is not permitted. However, they don't prevent the driver from being loaded since the init code returns 0. If at some point later the driver gets unloaded this will result in an oops while trying to deregister the (never registered) device. To avoid this, make init code return an error on paravirt or when microcode loading is disabled. The driver will then never be loaded. Signed-off-by: Boris Ostrovsky Reported-by: James Digwall Cc: stable@vger.kernel.org # 3.18 --- arch/x86/kernel/cpu/microcode/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 15c2909..36a8361 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -552,7 +552,7 @@ static int __init microcode_init(void) int error; if (paravirt_enabled() || dis_ucode_ldr) - return 0; + return -EINVAL; if (c->x86_vendor == X86_VENDOR_INTEL) microcode_ops = init_intel_microcode(); -- 1.9.3