From nobody Tue Apr 7 12:46:19 2026 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 211EFC4332F for ; Mon, 17 Oct 2022 09:57:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229660AbiJQJ5R (ORCPT ); Mon, 17 Oct 2022 05:57:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231229AbiJQJ5P (ORCPT ); Mon, 17 Oct 2022 05:57:15 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1196150070 for ; Mon, 17 Oct 2022 02:57:12 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MrXNN51ZZzVjWm; Mon, 17 Oct 2022 17:52:36 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 17 Oct 2022 17:57:10 +0800 Received: from ubuntu1804.huawei.com (10.67.175.36) by dggpemm500013.china.huawei.com (7.185.36.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 17 Oct 2022 17:57:10 +0800 From: Chen Zhongjin To: CC: , , Subject: [PATCH] firmware: dmi-sysfs: Fix null-ptr-deref in dmi_sysfs_register_handle Date: Mon, 17 Oct 2022 17:53:42 +0800 Message-ID: <20221017095342.2567-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.36] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" KASAN reported a null-ptr-deref error: KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 1373 Comm: modprobe Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:dmi_sysfs_entry_release ... Call Trace: kobject_put dmi_sysfs_register_handle (drivers/firmware/dmi-sysfs.c:540) dmi_sysfs dmi_decode_table (drivers/firmware/dmi_scan.c:133) dmi_walk (drivers/firmware/dmi_scan.c:1115) dmi_sysfs_init (drivers/firmware/dmi-sysfs.c:149) dmi_sysfs do_one_initcall (init/main.c:1296) ... Kernel panic - not syncing: Fatal exception Kernel Offset: 0x4000000 from 0xffffffff81000000 ---[ end Kernel panic - not syncing: Fatal exception ]--- It is because previous patch added kobject_put() to release the memory which will call dmi_sysfs_entry_release() and list_del(). However, list_add_tail(entry->list) is called after the error block, so the list_head is uninitialized and cannot be deleted. Because entry is allocated by kzalloc() so the list.prev is NULL in the error path. Check it in dmi_sysfs_entry_release() to avoid deleting uninitialized list_head. Fixes: 660ba678f999 ("firmware: dmi-sysfs: Fix memory leak in dmi_sysfs_reg= ister_handle") Signed-off-by: Chen Zhongjin --- drivers/firmware/dmi-sysfs.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c index 66727ad3361b..f8815eeed00c 100644 --- a/drivers/firmware/dmi-sysfs.c +++ b/drivers/firmware/dmi-sysfs.c @@ -557,9 +557,12 @@ static void dmi_sysfs_entry_release(struct kobject *ko= bj) { struct dmi_sysfs_entry *entry =3D to_entry(kobj); =20 - spin_lock(&entry_list_lock); - list_del(&entry->list); - spin_unlock(&entry_list_lock); + if (entry->list.prev !=3D NULL) { + spin_lock(&entry_list_lock); + list_del(&entry->list); + spin_unlock(&entry_list_lock); + } + kfree(entry); } =20 --=20 2.17.1