From patchwork Sat Oct 7 03:52:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Jinchao X-Patchwork-Id: 730675 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 39C31E81E14 for ; Sat, 7 Oct 2023 03:52:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234099AbjJGDw5 (ORCPT ); Fri, 6 Oct 2023 23:52:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234043AbjJGDw4 (ORCPT ); Fri, 6 Oct 2023 23:52:56 -0400 Received: from wxsgout04.xfusion.com (wxsgout03.xfusion.com [36.139.52.80]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4EC7CBD; Fri, 6 Oct 2023 20:52:52 -0700 (PDT) Received: from wuxshcsitd00600.xfusion.com (unknown [10.32.133.213]) by wxsgout04.xfusion.com (SkyGuard) with ESMTPS id 4S2WXb6BMszB0Y9b; Sat, 7 Oct 2023 11:50:23 +0800 (CST) Received: from localhost (10.82.147.3) by wuxshcsitd00600.xfusion.com (10.32.133.213) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Sat, 7 Oct 2023 11:52:33 +0800 Date: Sat, 7 Oct 2023 11:52:33 +0800 From: Wang Jinchao To: Steffen Klassert , Daniel Jordan , , CC: Subject: [PATCH v3] Fixes: 07928d9bfc81 ("padata: Remove broken queue flushing") Message-ID: MIME-Version: 1.0 Content-Disposition: inline X-Originating-IP: [10.82.147.3] X-ClientProxiedBy: wuxshcsitd00601.xfusion.com (10.32.135.241) To wuxshcsitd00600.xfusion.com (10.32.133.213) Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org In a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead to system UAF (Use-After-Free) issues. Due to the lengthy analysis of the pcrypt_aead01 function call, I'll describe the problem scenario using a simplified model: Suppose there's a user of padata named `user_function` that adheres to the padata requirement of calling `padata_free_shell` after `serial()` has been invoked, as demonstrated in the following code: ```c struct request { struct padata_priv padata; struct completion *done; }; void parallel(struct padata_priv *padata) { do_something(); } void serial(struct padata_priv *padata) { struct request *request = container_of(padata, struct request, padata); complete(request->done); } void user_function() { struct request request; DECLARE_COMPLETION(done) request->done = done; padata = &request.padata; padata->parallel = parallel; padata->serial = serial; padata_do_parallel(); wait_for_completion(&done); padata_free_shell(); } ``` In the corresponding padata.c file, there's the following code: ```c static void padata_serial_worker(struct work_struct *serial_work) { ... cnt = 0; while (!list_empty(&local_list)) { ... padata->serial(padata); cnt++; } local_bh_enable(); if (refcount_sub_and_test(cnt, &pd->refcnt)) padata_free_pd(pd); } ``` Because of the high system load and the accumulation of unexecuted softirq at this moment, `local_bh_enable()` in padata takes longer to execute than usual. Subsequently, when accessing `pd->refcnt`, `pd` has already been released by `padata_free_shell()`, resulting in a UAF issue with `pd->refcnt`. The fix is straightforward: add `refcount_dec_and_test` before calling `padata_free_pd` in `padata_free_shell`. Signed-off-by: Wang Jinchao Acked-by: Daniel Jordan --- V3: Include Daniel's ack V2: https://lore.kernel.org/all/ZRTLHY5A+VqIKhA2@fedora/ To satisfy Sparse, use rcu_dereference_protected. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202309270829.xHgTOMKw-lkp@intel.com/ V1: https://lore.kernel.org/all/ZRE4XvOOhz4HSOgR@fedora/ kernel/padata.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/padata.c b/kernel/padata.c index 222d60195de6..79d04a97ded6 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -1102,12 +1102,16 @@ EXPORT_SYMBOL(padata_alloc_shell); */ void padata_free_shell(struct padata_shell *ps) { + struct parallel_data *pd; + if (!ps) return; mutex_lock(&ps->pinst->lock); list_del(&ps->list); - padata_free_pd(rcu_dereference_protected(ps->pd, 1)); + pd = rcu_dereference_protected(ps->pd, 1); + if (refcount_dec_and_test(&pd->refcnt)) + padata_free_pd(rcu_dereference_protected(ps->pd, 1)); mutex_unlock(&ps->pinst->lock); kfree(ps);