From patchwork Tue May 26 18:52:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 225256 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=unavailable 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 A5AF6C433E0 for ; Tue, 26 May 2020 19:25:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84DF820721 for ; Tue, 26 May 2020 19:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590521157; bh=BJ0tO64MAidki1KuaMNtI00MVaxBlWf8j4Gm2u/+cZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=brNwkxO+5aDO/2Z5FkTzuYIDVBWnqvVPrSE8BbhdRtlqalIAwJpEfiCY8n9ff1Y2X Xspf/SL95X7peKnG1KFcHR3QBrDQocIdlxY1/uGaRK73FEutGGbz7MNMrmYQI9I+oe VGwJ+etQnOKHT9QKf+vSLMT0BgYvcnt6DABt7KCk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390566AbgEZTG0 (ORCPT ); Tue, 26 May 2020 15:06:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:34644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391570AbgEZTGZ (ORCPT ); Tue, 26 May 2020 15:06:25 -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 96A2220776; Tue, 26 May 2020 19:06:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519984; bh=BJ0tO64MAidki1KuaMNtI00MVaxBlWf8j4Gm2u/+cZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nuZuJzeegK53xgmauThOMay2cBGrJ9P9LSOOUhvrLy9jdWOzuF2+0oWJi7qHmqCpO xmgASUYZThxw6yWk4bY92MQSr/aaYmesHuF+BQeKMOpeQRn1H+ypvFe4qjkS+VrGGA IJu6qF9IOF0wubk5k0ndVjDS/vxJQnJYGhpOEyyY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Roberto Sassu , Dan Carpenter , Krzysztof Struczynski , Mimi Zohar , Sasha Levin Subject: [PATCH 5.4 013/111] evm: Fix a small race in init_desc() Date: Tue, 26 May 2020 20:52:31 +0200 Message-Id: <20200526183933.818958199@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183932.245016380@linuxfoundation.org> References: <20200526183932.245016380@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: Dan Carpenter [ Upstream commit 8433856947217ebb5697a8ff9c4c9cad4639a2cf ] The IS_ERR_OR_NULL() function has two conditions and if we got really unlucky we could hit a race where "ptr" started as an error pointer and then was set to NULL. Both conditions would be false even though the pointer at the end was NULL. This patch fixes the problem by ensuring that "*tfm" can only be NULL or valid. I have introduced a "tmp_tfm" variable to make that work. I also reversed a condition and pulled the code in one tab. Reported-by: Roberto Sassu Fixes: 53de3b080d5e ("evm: Check also if *tfm is an error pointer in init_desc()") Signed-off-by: Dan Carpenter Acked-by: Roberto Sassu Acked-by: Krzysztof Struczynski Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin --- security/integrity/evm/evm_crypto.c | 44 ++++++++++++++--------------- 1 file changed, 22 insertions(+), 22 deletions(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 302adeb2d37b..cc826c2767a3 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -75,7 +75,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) { long rc; const char *algo; - struct crypto_shash **tfm; + struct crypto_shash **tfm, *tmp_tfm; struct shash_desc *desc; if (type == EVM_XATTR_HMAC) { @@ -93,31 +93,31 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) algo = hash_algo_name[hash_algo]; } - if (IS_ERR_OR_NULL(*tfm)) { - mutex_lock(&mutex); - if (*tfm) - goto out; - *tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD); - if (IS_ERR(*tfm)) { - rc = PTR_ERR(*tfm); - pr_err("Can not allocate %s (reason: %ld)\n", algo, rc); - *tfm = NULL; + if (*tfm) + goto alloc; + mutex_lock(&mutex); + if (*tfm) + goto unlock; + + tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD); + if (IS_ERR(tmp_tfm)) { + pr_err("Can not allocate %s (reason: %ld)\n", algo, + PTR_ERR(tmp_tfm)); + mutex_unlock(&mutex); + return ERR_CAST(tmp_tfm); + } + if (type == EVM_XATTR_HMAC) { + rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len); + if (rc) { + crypto_free_shash(tmp_tfm); mutex_unlock(&mutex); return ERR_PTR(rc); } - if (type == EVM_XATTR_HMAC) { - rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len); - if (rc) { - crypto_free_shash(*tfm); - *tfm = NULL; - mutex_unlock(&mutex); - return ERR_PTR(rc); - } - } -out: - mutex_unlock(&mutex); } - + *tfm = tmp_tfm; +unlock: + mutex_unlock(&mutex); +alloc: desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm), GFP_KERNEL); if (!desc)