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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 4E5D4C2BA83 for ; Thu, 13 Feb 2020 16:06:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21C3120656 for ; Thu, 13 Feb 2020 16:06:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581609977; bh=PTPApXUgqmGll2uKZ0d6K4HlFTjkG6irNywR7Btj+yM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZY1PNJa9wp5/t4sLd0CBr/ht7rnviEqTSPr4FHuM/tFgcWMc/hllW1dNc4JUxy66i Py/yWzfNjOaCKUkFvQ3Kp8C2M5IqC4pK3A4Pxh/BwIotge0G9lPY2zGzn96nYi6ZTF yW7s1MIAJDuF1/Ezpj6CovUjcg1yFyNPRYKpFwTo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730137AbgBMQGQ (ORCPT ); Thu, 13 Feb 2020 11:06:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:35318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725781AbgBMPXk (ORCPT ); Thu, 13 Feb 2020 10:23:40 -0500 Received: from localhost (unknown [104.132.1.104]) (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 74EEF246C1; Thu, 13 Feb 2020 15:23:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581607419; bh=PTPApXUgqmGll2uKZ0d6K4HlFTjkG6irNywR7Btj+yM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zt/Y7fdp4UalFoZJtIvWx8grHSeK5SAWIxCUBEhc9V4F7Sgy462PmA+r6xS8Bk9Nd np9Is/W/xpB36nWZtG24nkgLP+M+uACugVYVnGwhRNtIcJ2D8FRCuL17Xyju34lIGP PFP6d3eZtlrewunIMf0Vy3stfm0gSGLqZS6tIDOc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Herbert Xu Subject: [PATCH 4.9 038/116] crypto: api - Fix race condition in crypto_spawn_alg Date: Thu, 13 Feb 2020 07:19:42 -0800 Message-Id: <20200213151857.948420705@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200213151842.259660170@linuxfoundation.org> References: <20200213151842.259660170@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: Herbert Xu commit 73669cc556462f4e50376538d77ee312142e8a8a upstream. The function crypto_spawn_alg is racy because it drops the lock before shooting the dying algorithm. The algorithm could disappear altogether before we shoot it. This patch fixes it by moving the shooting into the locked section. Fixes: 6bfd48096ff8 ("[CRYPTO] api: Added spawns") Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- crypto/algapi.c | 16 +++++----------- crypto/api.c | 3 +-- crypto/internal.h | 1 - 3 files changed, 6 insertions(+), 14 deletions(-) --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -662,22 +662,16 @@ EXPORT_SYMBOL_GPL(crypto_drop_spawn); static struct crypto_alg *crypto_spawn_alg(struct crypto_spawn *spawn) { struct crypto_alg *alg; - struct crypto_alg *alg2; down_read(&crypto_alg_sem); alg = spawn->alg; - alg2 = alg; - if (alg2) - alg2 = crypto_mod_get(alg2); - up_read(&crypto_alg_sem); - - if (!alg2) { - if (alg) - crypto_shoot_alg(alg); - return ERR_PTR(-EAGAIN); + if (alg && !crypto_mod_get(alg)) { + alg->cra_flags |= CRYPTO_ALG_DYING; + alg = NULL; } + up_read(&crypto_alg_sem); - return alg; + return alg ?: ERR_PTR(-EAGAIN); } struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type, --- a/crypto/api.c +++ b/crypto/api.c @@ -355,13 +355,12 @@ static unsigned int crypto_ctxsize(struc return len; } -void crypto_shoot_alg(struct crypto_alg *alg) +static void crypto_shoot_alg(struct crypto_alg *alg) { down_write(&crypto_alg_sem); alg->cra_flags |= CRYPTO_ALG_DYING; up_write(&crypto_alg_sem); } -EXPORT_SYMBOL_GPL(crypto_shoot_alg); struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type, u32 mask) --- a/crypto/internal.h +++ b/crypto/internal.h @@ -87,7 +87,6 @@ void crypto_alg_tested(const char *name, void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list, struct crypto_alg *nalg); void crypto_remove_final(struct list_head *list); -void crypto_shoot_alg(struct crypto_alg *alg); struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type, u32 mask); void *crypto_create_tfm(struct crypto_alg *alg,