From patchwork Mon Feb 10 12:32:38 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: 231641 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=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 31064C352A4 for ; Mon, 10 Feb 2020 13:32:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B11D20714 for ; Mon, 10 Feb 2020 13:32:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581341558; bh=1XafbSwsaOm7WMrwjLaRqhStQQ0xFhsk1hiOt1Q+6Ko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QeQ88HlxY0b+nBIT6TI1FRM2LiUo0Kz1ZhdsIIuIOUvg74ODDpIEvUzbiWt1uuLVD zUO343ZSiJV1iUUKmaSy20HJPwhiEe4ExMmOWQXnbYy/uBElveiP9COKdxdgLV4DTL l17HBInLtxvzGJB77YE2k58XHZ/4utLQ7ja18J9I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728686AbgBJNch (ORCPT ); Mon, 10 Feb 2020 08:32:37 -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 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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,