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,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 A6A1CC352A3 for ; Mon, 10 Feb 2020 13:32:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F37620714 for ; Mon, 10 Feb 2020 13:32:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581341561; bh=1XafbSwsaOm7WMrwjLaRqhStQQ0xFhsk1hiOt1Q+6Ko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=n4ymdnH5bLi02zFvFU/x5TvHuG9jgvgBYG64mlIRdVKMN6lrua02wFUBXQ9NOXeJO BKElyb4Q0o0NOEm5mEiqKypVIplPDEoPoxJPnSqZ0i3mAOxnrLhraim1ku6+tyrCQ3 FicxtBYSbbhHLD9YFbs8yqqeSUYvkAzqHBgB34pM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731264AbgBJNck (ORCPT ); Mon, 10 Feb 2020 08:32:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:53548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728081AbgBJMfn (ORCPT ); Mon, 10 Feb 2020 07:35:43 -0500 Received: from localhost (unknown [209.37.97.194]) (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 122AB2465D; Mon, 10 Feb 2020 12:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338143; bh=1XafbSwsaOm7WMrwjLaRqhStQQ0xFhsk1hiOt1Q+6Ko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gx5kZ+HaqW+DxAppv1x9GUB8fOhDEyqKKgss/twSiJZvrw7enFqqZZQvQ0obm9Yfj bkY451hksEqV0dnDOaAlAbeMYQrnHiL7t6HjXHDvLw6jTxpobxpTqIw6sBrYs0FooH vhyh6kjSD67KNPe6BBbBD+xipSH+pKjL6+wKtejU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Herbert Xu Subject: [PATCH 4.19 100/195] crypto: api - Fix race condition in crypto_spawn_alg Date: Mon, 10 Feb 2020 04:32:38 -0800 Message-Id: <20200210122314.957291864@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122305.731206734@linuxfoundation.org> References: <20200210122305.731206734@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 @@ -659,22 +659,16 @@ 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 @@ -349,13 +349,12 @@ 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 @@ -79,7 +79,6 @@ 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,