From patchwork Mon Apr 27 10:28:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 11511829 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BCF21913 for ; Mon, 27 Apr 2020 10:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A500D206E2 for ; Mon, 27 Apr 2020 10:32:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727124AbgD0KcA (ORCPT ); Mon, 27 Apr 2020 06:32:00 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2106 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726786AbgD0Kbm (ORCPT ); Mon, 27 Apr 2020 06:31:42 -0400 Received: from lhreml723-chm.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id AC11C564B7EF5C0124A8; Mon, 27 Apr 2020 11:31:40 +0100 (IST) Received: from fraeml714-chm.china.huawei.com (10.206.15.33) by lhreml723-chm.china.huawei.com (10.201.108.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Mon, 27 Apr 2020 11:31:40 +0100 Received: from roberto-HP-EliteDesk-800-G2-DM-65W.huawei.com (10.204.65.160) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Mon, 27 Apr 2020 12:31:39 +0200 From: Roberto Sassu To: , CC: , , , , , "Roberto Sassu" , Subject: [PATCH v2 2/6] evm: Check also if *tfm is an error pointer in init_desc() Date: Mon, 27 Apr 2020 12:28:56 +0200 Message-ID: <20200427102900.18887-2-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200427102900.18887-1-roberto.sassu@huawei.com> References: <20200427102900.18887-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.65.160] X-ClientProxiedBy: lhreml710-chm.china.huawei.com (10.201.108.61) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org This patch avoids a kernel panic due to accessing an error pointer set by crypto_alloc_shash(). It occurs especially when there are many files that require an unsupported algorithm, as it would increase the likelihood of the following race condition: Task A: *tfm = crypto_alloc_shash() <= error pointer Task B: if (*tfm == NULL) <= *tfm is not NULL, use it Task B: rc = crypto_shash_init(desc) <= panic Task A: *tfm = NULL This patch uses the IS_ERR_OR_NULL macro to determine whether or not a new crypto context must be created. Cc: stable@vger.kernel.org Fixes: d46eb3699502b ("evm: crypto hash replaced by shash") Co-developed-by: Krzysztof Struczynski Signed-off-by: Krzysztof Struczynski Signed-off-by: Roberto Sassu --- security/integrity/evm/evm_crypto.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 35682852ddea..77ad1e5a93e4 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -91,7 +91,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) algo = hash_algo_name[hash_algo]; } - if (*tfm == NULL) { + if (IS_ERR_OR_NULL(*tfm)) { mutex_lock(&mutex); if (*tfm) goto out;