From patchwork Tue May 26 18:52:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 225410 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA2F8C433DF for ; Tue, 26 May 2020 18:58:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AABC52086A for ; Tue, 26 May 2020 18:58:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519527; bh=iDeY2skZ4/3Sbynoo4JMtZ+fdIMyYtcW3coIfHV83mc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VHHhSHhr6P6TWBhMWLXfRc+XUz1lyzg2NCMR8qhkiyanS6QCbXrx0AThRRExL6TzW uf0jwOUxYQzp2WP6TN9WSzSdyHa9k8K6J+6GT8B9SJJ5Eoc0J+DQbylZFOZ71Ybjft 1rymNiHAiPuEw3e1c0y7eqkLYpeOGg0uTyS/ztUI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390395AbgEZS6q (ORCPT ); Tue, 26 May 2020 14:58:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:52306 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390392AbgEZS6p (ORCPT ); Tue, 26 May 2020 14:58:45 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C641020849; Tue, 26 May 2020 18:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519525; bh=iDeY2skZ4/3Sbynoo4JMtZ+fdIMyYtcW3coIfHV83mc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZRB236cGUcAp+LMzBGZQ/GqHOvmAb0Y18wKZyTx6YGufV1HqDA2P7Z6ZnqgdW2zln oYCvIV+H0YFp4eFPuSd44gZjVPU3z6dAwI3P6LtSBW72OkDjD8waAKrUikxqfTWETg aqQi4ABAwzselq8tXTDfFsemA+mwsaqtBwohf5u4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Krzysztof Struczynski , Roberto Sassu , Mimi Zohar , Sasha Levin Subject: [PATCH 4.9 06/64] evm: Check also if *tfm is an error pointer in init_desc() Date: Tue, 26 May 2020 20:52:35 +0200 Message-Id: <20200526183915.284720219@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183913.064413230@linuxfoundation.org> References: <20200526183913.064413230@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Roberto Sassu [ Upstream commit 53de3b080d5eae31d0de219617155dcc34e7d698 ] 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 Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin --- 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 c783fefa558a..e034dc21421e 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -90,7 +90,7 @@ static struct shash_desc *init_desc(char type) algo = evm_hash; } - if (*tfm == NULL) { + if (IS_ERR_OR_NULL(*tfm)) { mutex_lock(&mutex); if (*tfm) goto out;