Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754929AbdHYKFB (ORCPT ); Fri, 25 Aug 2017 06:05:01 -0400 Received: from mail.skyhub.de ([5.9.137.197]:55056 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754838AbdHYKE7 (ORCPT ); Fri, 25 Aug 2017 06:04:59 -0400 Date: Fri, 25 Aug 2017 12:04:56 +0200 From: Borislav Petkov To: x86-ml Cc: Dan Carpenter , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [PATCH] x86/microcode/intel: Improve microcode patches saving flow Message-ID: <20170825100456.n236w3jebteokfd6@pd.tnic> References: <20170822211335.r7wcfcisdlq2xwgz@pd.tnic> <20170824201557.ev4ebslf6sg6xmne@mwanda> <20170824204714.jedeaphwmou5qafd@pd.tnic> <20170824205510.zy574qloxb4tsokq@mwanda> <20170824205844.3wkrq6vb7kv45vnv@pd.tnic> <20170824210847.hypvvpzf5pjhppyt@mwanda> <20170824211205.jpvmzzrm72vcb4xf@pd.tnic> <20170825090626.okc6reqltb5k4hip@pd.tnic> <20170825091228.acxl2pizbqe7ijnf@mwanda> <20170825091406.zytkd2pb5v6zxzrz@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170825091406.zytkd2pb5v6zxzrz@pd.tnic> 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: 2764 Lines: 97 From: Borislav Petkov Avoid potentially dereferencing a NULL pointer when saving a microcode patch for early loading on the application processors. While at it, drop the IS_ERR() checking in favor of simpler, NULL-ptr checks which are sufficient and rename __alloc_microcode_buf() to memdup_patch() to more precisely denote what it does. No functionality change. Reported-by: Dan Carpenter Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/microcode/intel.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c index 59edbe9d4ccb..8f7a9bbad514 100644 --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -146,18 +146,18 @@ 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; p = kzalloc(sizeof(struct ucode_patch), GFP_KERNEL); if (!p) - return ERR_PTR(-ENOMEM); + return NULL; p->data = kmemdup(data, size, GFP_KERNEL); if (!p->data) { kfree(p); - return ERR_PTR(-ENOMEM); + return NULL; } return p; @@ -183,8 +183,8 @@ 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 (!p) pr_err("Error allocating buffer %p\n", data); else list_replace(&iter->plist, &p->plist); @@ -196,24 +196,25 @@ 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 (!p) pr_err("Error allocating buffer for %p\n", data); else list_add_tail(&p->plist, µcode_cache); } + if (!p) + return; + /* * Save for early loading. On 32-bit, that needs to be a physical * address as the APs are running from physical addresses, before * paging has been enabled. */ - if (p) { - if (IS_ENABLED(CONFIG_X86_32)) - intel_ucode_patch = (struct microcode_intel *)__pa_nodebug(p->data); - else - intel_ucode_patch = p->data; - } + if (IS_ENABLED(CONFIG_X86_32)) + intel_ucode_patch = (struct microcode_intel *)__pa_nodebug(p->data); + else + intel_ucode_patch = p->data; } static int microcode_sanity_check(void *mc, int print_err) -- 2.13.0 -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.