From patchwork Thu Aug 3 09:59:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 710343 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 027C5C04A6A for ; Thu, 3 Aug 2023 10:00:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235206AbjHCKAQ (ORCPT ); Thu, 3 Aug 2023 06:00:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235158AbjHCJ7l (ORCPT ); Thu, 3 Aug 2023 05:59:41 -0400 Received: from 167-179-156-38.a7b39c.syd.nbn.aussiebb.net (167-179-156-38.a7b39c.syd.nbn.aussiebb.net [167.179.156.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 305FC3A9A; Thu, 3 Aug 2023 02:59:36 -0700 (PDT) Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1qRV7A-003BTH-4d; Thu, 03 Aug 2023 17:59:29 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Thu, 03 Aug 2023 17:59:28 +0800 Date: Thu, 3 Aug 2023 17:59:28 +0800 From: Herbert Xu To: Florent Revest Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sctp@vger.kernel.org, davem@davemloft.net, hillf.zj@alibaba-inc.com, marcelo.leitner@gmail.com, lucien.xin@gmail.com Subject: crypto: api - Use work queue in crypto_destroy_instance Message-ID: References: <20230802170923.1151605-1-revest@chromium.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230802170923.1151605-1-revest@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, Aug 02, 2023 at 07:09:22PM +0200, Florent Revest wrote: > > I found that the following program reliably reproduces a "BUG: sleeping function > called from invalid context" backtrace in crypto code: Great detective work! And thanks for cc'ing me :) This is definitely a bug in the Crypto API. Although it's hard to trigger because you need to unregister the instance before the last user frees it in atomic context. The fact that it triggers for your test program probably means that we're not creating the template correctly and it gets unregistered as soon as it's created. As to the fix I think we should move the work into crypto_destroy_instance since that's the function that is being called from atomic context and then does something that should only be done from process context. So here's my patch based on your work: ---8<--- The function crypto_drop_spawn expects to be called in process context. However, when an instance is unregistered while it still has active users, the last user may cause the instance to be freed in atomic context. Fix this by delaying the freeing to a work queue. Fixes: 6bfd48096ff8 ("[CRYPTO] api: Added spawns") Reported-by: Florent Revest Reported-by: syzbot+d769eed29cc42d75e2a3@syzkaller.appspotmail.com Reported-by: syzbot+610ec0671f51e838436e@syzkaller.appspotmail.com Signed-off-by: Herbert Xu diff --git a/crypto/algapi.c b/crypto/algapi.c index 5e7cd603d489..4fe95c448047 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "internal.h" @@ -74,15 +75,26 @@ static void crypto_free_instance(struct crypto_instance *inst) inst->alg.cra_type->free(inst); } -static void crypto_destroy_instance(struct crypto_alg *alg) +static void crypto_destroy_instance_workfn(struct work_struct *w) { - struct crypto_instance *inst = (void *)alg; + struct crypto_instance *inst = container_of(w, struct crypto_instance, + free_work); struct crypto_template *tmpl = inst->tmpl; crypto_free_instance(inst); crypto_tmpl_put(tmpl); } +static void crypto_destroy_instance(struct crypto_alg *alg) +{ + struct crypto_instance *inst = container_of(alg, + struct crypto_instance, + alg); + + INIT_WORK(&inst->free_work, crypto_destroy_instance_workfn); + schedule_work(&inst->free_work); +} + /* * This function adds a spawn to the list secondary_spawns which * will be used at the end of crypto_remove_spawns to unregister diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index 6156161b181f..ca86f4c6ba43 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -12,6 +12,7 @@ #include #include #include +#include /* * Maximum values for blocksize and alignmask, used to allocate @@ -82,6 +83,8 @@ struct crypto_instance { struct crypto_spawn *spawns; }; + struct work_struct free_work; + void *__ctx[] CRYPTO_MINALIGN_ATTR; };