Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753627AbdHXUrY (ORCPT ); Thu, 24 Aug 2017 16:47:24 -0400 Received: from mail.skyhub.de ([5.9.137.197]:58690 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752875AbdHXUrX (ORCPT ); Thu, 24 Aug 2017 16:47:23 -0400 Date: Thu, 24 Aug 2017 22:47:14 +0200 From: Borislav Petkov To: Dan Carpenter Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH v2] x86/microcode: Silence a static checker warning Message-ID: <20170824204714.jedeaphwmou5qafd@pd.tnic> References: <20170822211335.r7wcfcisdlq2xwgz@pd.tnic> <20170824201557.ev4ebslf6sg6xmne@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170824201557.ev4ebslf6sg6xmne@mwanda> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2259 Lines: 74 On Thu, Aug 24, 2017 at 11:15:57PM +0300, Dan Carpenter wrote: > The code here prints an error if "p" is an error pointer but it still > dereferences it at the end of the function when it does: > > intel_ucode_patch = (struct microcode_intel *)__pa_nodebug(p->data); > > We can just return early instead. > > Signed-off-by: Dan Carpenter > --- > v2: return early instead checking for IS_ERR_OR_NULL() at the end. > > We have to keep the final check whether "p" is NULL to handle the > situation were we set "prev_found = true;" but then hit the continue > statement instead of allocating "p". I think we want to something more like this (not exit the loop if the allocation fails). But I need to look at the again on a clear head:a --- diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index 59edbe9d4ccb..0179f0fd8a79 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -146,7 +146,7 @@ static bool microcode_matches(struct microcode_header_intel *mc_header, return false; } -static struct ucode_patch *__alloc_microcode_buf(void *data, unsigned int size) +static struct ucode_patch *memdup_patch(void *data, unsigned int size) { struct ucode_patch *p; @@ -183,11 +183,13 @@ static void save_microcode_patch(void *data, unsigned int size) if (mc_hdr->rev <= mc_saved_hdr->rev) continue; - p = __alloc_microcode_buf(data, size); - if (IS_ERR(p)) + p = memdup_patch(data, size); + if (IS_ERR(p)) { pr_err("Error allocating buffer %p\n", data); - else - list_replace(&iter->plist, &p->plist); + continue; + } + + list_replace(&iter->plist, &p->plist); } } @@ -196,11 +198,12 @@ static void save_microcode_patch(void *data, unsigned int size) * newly found. */ if (!prev_found) { - p = __alloc_microcode_buf(data, size); - if (IS_ERR(p)) + p = memdup_patch(data, size); + if (IS_ERR(p)) { pr_err("Error allocating buffer for %p\n", data); - else - list_add_tail(&p->plist, µcode_cache); + return; + } + list_add_tail(&p->plist, µcode_cache); } /* -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.