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[23.128.96.36]) by mx.google.com with ESMTPS id z17-20020a170903409100b001c4605546b5si4679379plc.42.2023.10.06.20.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Oct 2023 20:53:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) client-ip=23.128.96.36; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by pete.vger.email (Postfix) with ESMTP id 0B87682CBAF5; Fri, 6 Oct 2023 20:53:43 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at pete.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343500AbjJGDw6 (ORCPT + 18 others); Fri, 6 Oct 2023 23:52:58 -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) X-Spam-Status: No, score=2.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on pete.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (pete.vger.email [0.0.0.0]); Fri, 06 Oct 2023 20:53:43 -0700 (PDT) X-Spam-Level: ** X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779067335879232538 X-GMAIL-MSGID: 1779067335879232538 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);