From mboxrd@z Thu Jan 1 00:00:00 1970 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 6C3FDC433E1 for ; Tue, 26 May 2020 19:11:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C6B720888 for ; Tue, 26 May 2020 19:11:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520285; bh=BJ0tO64MAidki1KuaMNtI00MVaxBlWf8j4Gm2u/+cZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=XiPtFpFGOQF3FcTWbHqab7zZ0uN98JPIfijikV3q8GE7WXD+kb3ron4EtslnU8IUw zdS37xFkZ7VBmHSV7kziJLv5tUdng8MzbH4RyaGK234VG0wK7PGFsCJ6mcDBR+oxoL ujQIauv32BTSSg3jvipcNdUV0vdAcBdCcjTmo5AM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404060AbgEZTLY (ORCPT ); Tue, 26 May 2020 15:11:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:40616 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389286AbgEZTLQ (ORCPT ); Tue, 26 May 2020 15:11:16 -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 CD76E20888; Tue, 26 May 2020 19:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520275; bh=BJ0tO64MAidki1KuaMNtI00MVaxBlWf8j4Gm2u/+cZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tDLJrjAGUTFJNdaTSQLPkNq23QtyJ49jNo6v/r0chzTCDTmrZhiCdLl1Mvy5YURFU Uof7dMqRF5ChDM0DmeMH7q0NUgY8rJvYW5ulxAmvjjNztFxxZlO+aQcnENkuCJC/0w QYFK5f+dUV2a2C4TzrjfpUEjEhfBcC7FcwS8TgoU= 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 5.6 016/126] evm: Fix a small race in init_desc() Date: Tue, 26 May 2020 20:52:33 +0200 Message-Id: <20200526183938.974820180@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183937.471379031@linuxfoundation.org> References: <20200526183937.471379031@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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) -- 2.25.1