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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 23282C04AB4 for ; Wed, 15 May 2019 00:57:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCE5D2084E for ; Wed, 15 May 2019 00:57:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="m7RCFrds" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726148AbfEOA5k (ORCPT ); Tue, 14 May 2019 20:57:40 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:46708 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726044AbfEOA5k (ORCPT ); Tue, 14 May 2019 20:57:40 -0400 Received: by mail-pf1-f193.google.com with SMTP id y11so383823pfm.13; Tue, 14 May 2019 17:57:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=827ciu3T2iZYONCrSFCiqW6GJEVdj8Q9eDG+GtWLJNE=; b=m7RCFrdsQIKSxSps+bSxy8t2r1fRIrVJsVaQgcwF7zU6uLYKr767N9oeGgyaXConLw nKoLwdA8v2z87muCGWYxu8Iqwp49l+Ucm4pSIvU0L/FWEfPjfTryVXTM4maVl3Mzg7Ue 4CnwUGk33ljD4CPqtfLuTvD3BVpbyuX//BfxTLzrpba+L/gheLXJiL75CfsiYXOhMyL9 9i8tcRY0Ya2t27Owr+OdZpp760shDVjpUGHayp/tmHnhyA3pwczTQMXUamWzKe+aE/Zc eOvERtJc7ypnLOGlvVzstbfiMAreCJeeyrUp60rOYeQPMQmGFOnjbroBr/hHAihRE5TO fpeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=827ciu3T2iZYONCrSFCiqW6GJEVdj8Q9eDG+GtWLJNE=; b=kN47peqbeZ9iplSPxwRr/5ZdOa85HqwDUKakHV1C6Lupuo5cA6tnHgvQBC8YC5JKTP 4ujSLExA4+vpQ9umkV8Qf7c3VoiuSHFu4I22Y5Cen6WtBoyg/OxkHK5HbBD8QTnL2IEb ygCjEG3Q8mXU3c27UNy5Y/vHOF1JsngEtCkqHwwdeIaCPVrFah/BXMq6DATcOiSFy+Tv ALD3OTp9M/RXKdiv0BSLjks2pTjmgc8+JWE2X2CW/u5CsPIL1cMgsm2hzch/z6wtMEnF uGX5ODBeAeYTEFL1PODe37pJoDqsZy1NEFt+siYvd5rtplwFDwbXPldwYobgfVwbanrv q6XQ== X-Gm-Message-State: APjAAAUzyIAuC6u50z2IBCFfTDqNv8WllCuhjHRbnrLcjDd1+8ojKjqq BMeW77wJ9u0oqiwRuOWIyEA= X-Google-Smtp-Source: APXvYqx8fp2ri/vGzHAUhFXH4NHUxtuC8zlmj1Cp+aDLvMW9U7GQlJkckcP2D/wDckY+5K9WhtKAFQ== X-Received: by 2002:a62:ac0a:: with SMTP id v10mr44572897pfe.57.1557881859232; Tue, 14 May 2019 17:57:39 -0700 (PDT) Received: from ubuntu.localdomain ([104.238.150.158]) by smtp.gmail.com with ESMTPSA id s137sm409319pfc.119.2019.05.14.17.57.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 May 2019 17:57:38 -0700 (PDT) From: Muchun Song To: gregkh@linuxfoundation.org, rafael@kernel.org, benh@kernel.crashing.org, prsood@codeaurora.org, mojha@codeaurora.org, gkohli@codeaurora.org Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, zhaowuyun@wingtech.com Subject: [PATCH v3] driver core: Fix use-after-free and double free on glue directory Date: Wed, 15 May 2019 08:57:16 +0800 Message-Id: <20190515005716.4019-1-smuchun@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org There is a race condition between removing glue directory and adding a new device under the glue directory. It can be reproduced in following test: path 1: Add the child device under glue dir device_add() get_device_parent() mutex_lock(&gdp_mutex); .... /*find parent from glue_dirs.list*/ list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry) if (k->parent == parent_kobj) { kobj = kobject_get(k); break; } .... mutex_unlock(&gdp_mutex); .... .... kobject_add() kobject_add_internal() create_dir() sysfs_create_dir_ns() if (kobj->parent) parent = kobj->parent->sd; .... kernfs_create_dir_ns(parent) kernfs_new_node() kernfs_get(parent) .... /* link in */ rc = kernfs_add_one(kn); if (!rc) return kn; kernfs_put(kn) .... repeat: kmem_cache_free(kn) kn = parent; if (kn) { if (atomic_dec_and_test(&kn->count)) goto repeat; } .... path2: Remove last child device under glue dir device_del() cleanup_device_parent() cleanup_glue_dir() mutex_lock(&gdp_mutex); if (!kobject_has_children(glue_dir)) kobject_del(glue_dir); kobject_put(glue_dir); mutex_unlock(&gdp_mutex); Before path2 remove last child device under glue dir, If path1 add a new device under glue dir, the glue_dir kobject reference count will be increase to 2 via kobject_get(k) in get_device_parent(). And path1 has been called kernfs_new_node(), but not call kernfs_get(parent). Meanwhile, path2 call kobject_del(glue_dir) beacause 0 is returned by kobject_has_children(). This result in glue_dir->sd is freed and it's reference count will be 0. Then path1 call kernfs_get(parent) will trigger a warning in kernfs_get()(WARN_ON(!atomic_read(&kn->count))) and increase it's reference count to 1. Because glue_dir->sd is freed by path2, the next call kernfs_add_one() by path1 will fail(This is also use-after-free) and call atomic_dec_and_test() to decrease reference count. Because the reference count is decremented to 0, it will also call kmem_cache_free() to free glue_dir->sd again. This will result in double free. In order to avoid this happening, we we should not call kobject_del() on path2 when the reference count of glue_dir is greater than 1. So we add a conditional statement to fix it. The following calltrace is captured in kernel 4.14 with the following patch applied: commit 726e41097920 ("drivers: core: Remove glue dirs from sysfs earlier") -------------------------------------------------------------------------- [ 3.633703] WARNING: CPU: 4 PID: 513 at .../fs/kernfs/dir.c:494 Here is WARN_ON(!atomic_read(&kn->count) in kernfs_get(). .... [ 3.633986] Call trace: [ 3.633991] kernfs_create_dir_ns+0xa8/0xb0 [ 3.633994] sysfs_create_dir_ns+0x54/0xe8 [ 3.634001] kobject_add_internal+0x22c/0x3f0 [ 3.634005] kobject_add+0xe4/0x118 [ 3.634011] device_add+0x200/0x870 [ 3.634017] _request_firmware+0x958/0xc38 [ 3.634020] request_firmware_into_buf+0x4c/0x70 .... [ 3.634064] kernel BUG at .../mm/slub.c:294! Here is BUG_ON(object == fp) in set_freepointer(). .... [ 3.634346] Call trace: [ 3.634351] kmem_cache_free+0x504/0x6b8 [ 3.634355] kernfs_put+0x14c/0x1d8 [ 3.634359] kernfs_create_dir_ns+0x88/0xb0 [ 3.634362] sysfs_create_dir_ns+0x54/0xe8 [ 3.634366] kobject_add_internal+0x22c/0x3f0 [ 3.634370] kobject_add+0xe4/0x118 [ 3.634374] device_add+0x200/0x870 [ 3.634378] _request_firmware+0x958/0xc38 [ 3.634381] request_firmware_into_buf+0x4c/0x70 -------------------------------------------------------------------------- Fixes: 726e41097920 ("drivers: core: Remove glue dirs from sysfs earlier") Signed-off-by: Muchun Song --- Change in v3: add change log. Change in v2: Fix device_move() also. drivers/base/core.c | 47 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 38 insertions(+), 9 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 4aeaa0c92bda..e7810329223a 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1739,8 +1739,9 @@ class_dir_create_and_add(struct class *class, struct kobject *parent_kobj) static DEFINE_MUTEX(gdp_mutex); -static struct kobject *get_device_parent(struct device *dev, - struct device *parent) +static struct kobject *__get_device_parent(struct device *dev, + struct device *parent, + bool lock) { if (dev->class) { struct kobject *kobj = NULL; @@ -1779,14 +1780,16 @@ static struct kobject *get_device_parent(struct device *dev, } spin_unlock(&dev->class->p->glue_dirs.list_lock); if (kobj) { - mutex_unlock(&gdp_mutex); + if (!lock) + mutex_unlock(&gdp_mutex); return kobj; } /* or create a new class-directory at the parent device */ k = class_dir_create_and_add(dev->class, parent_kobj); /* do not emit an uevent for this simple "glue" directory */ - mutex_unlock(&gdp_mutex); + if (!lock || IS_ERR(k)) + mutex_unlock(&gdp_mutex); return k; } @@ -1799,6 +1802,19 @@ static struct kobject *get_device_parent(struct device *dev, return NULL; } +static inline struct kobject *get_device_parent(struct device *dev, + struct device *parent) +{ + return __get_device_parent(dev, parent, false); +} + +static inline struct kobject * +get_device_parent_locked_if_glue_dir(struct device *dev, + struct device *parent) +{ + return __get_device_parent(dev, parent, true); +} + static inline bool live_in_glue_dir(struct kobject *kobj, struct device *dev) { @@ -1831,6 +1847,16 @@ static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir) mutex_unlock(&gdp_mutex); } +static inline void unlock_if_glue_dir(struct device *dev, + struct kobject *glue_dir) +{ + /* see if we live in a "glue" directory */ + if (!live_in_glue_dir(glue_dir, dev)) + return; + + mutex_unlock(&gdp_mutex); +} + static int device_add_class_symlinks(struct device *dev) { struct device_node *of_node = dev_of_node(dev); @@ -2040,7 +2066,7 @@ int device_add(struct device *dev) pr_debug("device: '%s': %s\n", dev_name(dev), __func__); parent = get_device(dev->parent); - kobj = get_device_parent(dev, parent); + kobj = get_device_parent_locked_if_glue_dir(dev, parent); if (IS_ERR(kobj)) { error = PTR_ERR(kobj); goto parent_error; @@ -2055,10 +2081,12 @@ int device_add(struct device *dev) /* first, register with generic layer. */ /* we require the name to be set before, and pass NULL */ error = kobject_add(&dev->kobj, dev->kobj.parent, NULL); - if (error) { - glue_dir = get_glue_dir(dev); + + glue_dir = get_glue_dir(dev); + unlock_if_glue_dir(dev, glue_dir); + + if (error) goto Error; - } /* notify platform of device entry */ error = device_platform_notify(dev, KOBJ_ADD); @@ -2972,7 +3000,7 @@ int device_move(struct device *dev, struct device *new_parent, device_pm_lock(); new_parent = get_device(new_parent); - new_parent_kobj = get_device_parent(dev, new_parent); + new_parent_kobj = get_device_parent_locked_if_glue_dir(dev, new_parent); if (IS_ERR(new_parent_kobj)) { error = PTR_ERR(new_parent_kobj); put_device(new_parent); @@ -2982,6 +3010,7 @@ int device_move(struct device *dev, struct device *new_parent, pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev), __func__, new_parent ? dev_name(new_parent) : ""); error = kobject_move(&dev->kobj, new_parent_kobj); + unlock_if_glue_dir(dev, new_parent_kobj); if (error) { cleanup_glue_dir(dev, new_parent_kobj); put_device(new_parent); -- 2.17.1