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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 B70E6C07E9C for ; Tue, 13 Jul 2021 02:50:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A9796120A for ; Tue, 13 Jul 2021 02:50:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234035AbhGMCwv (ORCPT ); Mon, 12 Jul 2021 22:52:51 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:14072 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233444AbhGMCwu (ORCPT ); Mon, 12 Jul 2021 22:52:50 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GP4ll1tB9zYrlr; Tue, 13 Jul 2021 10:46:43 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 13 Jul 2021 10:49:59 +0800 Received: from thunder-town.china.huawei.com (10.174.179.0) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 13 Jul 2021 10:49:59 +0800 From: Zhen Lei To: Luis Chamberlain , Greg Kroah-Hartman , "Rafael J . Wysocki" , "Ming Lei" , linux-kernel CC: Zhen Lei Subject: [PATCH 1/1] firmware: fix use-after-free in _request_firmware() Date: Tue, 13 Jul 2021 10:49:42 +0800 Message-ID: <20210713024942.2881-1-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.174.179.0] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org CPU0 CPU1 __device_uncache_fw_images(): assign_fw(): fw_cache_piggyback_on_request() <----- P0 spin_lock(&fwc->name_lock); ... list_del(&fce->list); spin_unlock(&fwc->name_lock); uncache_firmware(fce->name); <----- P1 kref_get(&fw_priv->ref); If CPU1 is interrupted at position P0, the new 'fce' has been added to the list fwc->fw_names by the fw_cache_piggyback_on_request(). In this case, CPU0 executes __device_uncache_fw_images() and will be able to see it when it traverses list fwc->fw_names. Before CPU1 executes kref_get() at P1, if CPU0 further executes uncache_firmware(), the count of fw_priv->ref may decrease to 0, causing fw_priv to be released in advance. Move kref_get() to the lock protection range of fwc->name_lock to fix it. Fixes: ac39b3ea73aa ("firmware loader: let caching firmware piggyback on loading firmware") Signed-off-by: Zhen Lei --- drivers/base/firmware_loader/main.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c index 4fdb8219cd08..2f267b8d2fd9 100644 --- a/drivers/base/firmware_loader/main.c +++ b/drivers/base/firmware_loader/main.c @@ -165,7 +165,7 @@ static inline int fw_state_wait(struct fw_priv *fw_priv) return __fw_state_wait_common(fw_priv, MAX_SCHEDULE_TIMEOUT); } -static int fw_cache_piggyback_on_request(const char *name); +static void fw_cache_piggyback_on_request(struct fw_priv *fw_priv); static struct fw_priv *__allocate_fw_priv(const char *fw_name, struct firmware_cache *fwc, @@ -707,10 +707,8 @@ int assign_fw(struct firmware *fw, struct device *device) * on request firmware. */ if (!(fw_priv->opt_flags & FW_OPT_NOCACHE) && - fw_priv->fwc->state == FW_LOADER_START_CACHE) { - if (fw_cache_piggyback_on_request(fw_priv->fw_name)) - kref_get(&fw_priv->ref); - } + fw_priv->fwc->state == FW_LOADER_START_CACHE) + fw_cache_piggyback_on_request(fw_priv); /* pass the pages buffer to driver at the last minute */ fw_set_page_data(fw_priv, fw); @@ -1257,11 +1255,11 @@ static int __fw_entry_found(const char *name) return 0; } -static int fw_cache_piggyback_on_request(const char *name) +static void fw_cache_piggyback_on_request(struct fw_priv *fw_priv) { - struct firmware_cache *fwc = &fw_cache; + const char *name = fw_priv->fw_name; + struct firmware_cache *fwc = fw_priv->fwc; struct fw_cache_entry *fce; - int ret = 0; spin_lock(&fwc->name_lock); if (__fw_entry_found(name)) @@ -1269,13 +1267,12 @@ static int fw_cache_piggyback_on_request(const char *name) fce = alloc_fw_cache_entry(name); if (fce) { - ret = 1; list_add(&fce->list, &fwc->fw_names); + kref_get(&fw_priv->ref); pr_debug("%s: fw: %s\n", __func__, name); } found: spin_unlock(&fwc->name_lock); - return ret; } static void free_fw_cache_entry(struct fw_cache_entry *fce) @@ -1506,9 +1503,8 @@ static inline void unregister_fw_pm_ops(void) unregister_pm_notifier(&fw_cache.pm_notify); } #else -static int fw_cache_piggyback_on_request(const char *name) +static void fw_cache_piggyback_on_request(struct fw_priv *fw_priv) { - return 0; } static inline int register_fw_pm_ops(void) { -- 2.25.1