From nobody Sun Nov 24 17:36:38 2024 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 806B517C225; Sun, 3 Nov 2024 16:06:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730649973; cv=none; b=DvVnrG5JyZ5rv1EANe5gfXrqla3wXWDyBW5zyWJl4HCYwn+TITt9LZMqDWo0nd8TAnfeqfq3XbZikXvvlq95ncYEpsaILXjQqoa1NE6Aqgq+Ek1QRwJqt4hG6U76qLEqDk47P75yJ82S0GQsswd/vsiRq/CbINIlEim3Yzxr5GY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730649973; c=relaxed/simple; bh=a1CL7nZDwxH2JJ+sVL+MznUaUioo4sCtbj+JOdKvfJU=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Yb/71FMqv5HfewZhiaefTqYZS//gNAD0wZeE9TVfOoQaGmprINkFjUs7exlEt1DsdP8h1pp0obT2s1YpsMJ3m8odMO6K1QJf2S4ucxIL0ZPF1rQWwZYVTT14nPp1RMJz25cF5V8s9SDxdTM6T1aoYTVEUbV+/R7CNeZge4AZWg4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=CDNu1dBs; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="CDNu1dBs" Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 4A3FnO4B010920; Sun, 3 Nov 2024 16:05:52 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= cc:content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=qcppdkim1; bh=vySMAgNa6I+8OJZVe/9XBT orqwJ2DVPTOUBP8+qMTMw=; b=CDNu1dBsEk1cnkzeJ+2FgEWdyyWtvX3G43Tlll R9HKaRXz4GC9O/ngDcg4PcwJhX5lNyOpp28niQe5CZK6AosfLuQVPOgQaTCZaVyC WPni2vQ9q3ZNO95+hDKkr5aKoEqkbQHfJCC8GR00U2RAgetkzIbt195R9kSIynj/ MCRthn5S13IW3mizFZieNIYnWgIQ6lUM/mYDjOmW9C9V5FGYUSPIVcQFSJW3GG7R lt3XQBcMLQ/7IjVL8KI4ysp1gIU823RfqKhYKHacUwsA6uy+zGxfasul4Uj1YV3Z tBbuJds337XfB6BDnI1p+pADN/bNErshutt8GRmRbhS/i5BQ== Received: from nasanppmta03.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 42nd5cj810-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 03 Nov 2024 16:05:52 +0000 (GMT) Received: from nasanex01c.na.qualcomm.com (nasanex01c.na.qualcomm.com [10.45.79.139]) by NASANPPMTA03.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 4A3G5pfp004231 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 3 Nov 2024 16:05:51 GMT Received: from hu-mojha-hyd.qualcomm.com (10.80.80.8) by nasanex01c.na.qualcomm.com (10.45.79.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Sun, 3 Nov 2024 08:05:49 -0800 From: Mukesh Ojha To: Pavel Machek , Lee Jones CC: , , Mukesh Ojha Subject: [PATCH v3] leds: class: Protect brightness_show() with led_cdev->led_access mutex Date: Sun, 3 Nov 2024 21:35:27 +0530 Message-ID: <20241103160527.82487-1-quic_mojha@quicinc.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01c.na.qualcomm.com (10.45.79.139) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: e7lh0d3YgPegGp3l9aEVxEWqnA7njukx X-Proofpoint-GUID: e7lh0d3YgPegGp3l9aEVxEWqnA7njukx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 mlxscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 adultscore=0 clxscore=1015 phishscore=0 malwarescore=0 mlxlogscore=705 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2411030145 Content-Type: text/plain; charset="utf-8" There is NULL pointer issue observed if from Process A where hid device being added which results in adding a led_cdev addition and later a another call to access of led_cdev attribute from Process B can result in NULL pointer issue. Use mutex led_cdev->led_access to protect access to led->cdev and its attribute inside brightness_show() and max_brightness_show() and also update the comment for mutex that it should be used to protect the led class device fields. Process A Process B kthread+0x114 worker_thread+0x244 process_scheduled_works+0x248 uhid_device_add_worker+0x24 hid_add_device+0x120 device_add+0x268 bus_probe_device+0x94 device_initial_probe+0x14 __device_attach+0xfc bus_for_each_drv+0x10c __device_attach_driver+0x14c driver_probe_device+0x3c __driver_probe_device+0xa0 really_probe+0x190 hid_device_probe+0x130 ps_probe+0x990 ps_led_register+0x94 devm_led_classdev_register_ext+0x58 led_classdev_register_ext+0x1f8 device_create_with_groups+0x48 device_create_groups_vargs+0xc8 device_add+0x244 kobject_uevent+0x14 kobject_uevent_env[jt]+0x224 mutex_unlock[jt]+0xc4 __mutex_unlock_slowpath+0xd4 wake_up_q+0x70 try_to_wake_up[jt]+0x48c preempt_schedule_common+0x28 __schedule+0x628 __switch_to+0x174 el0t_64_sync+0x1a8/0x1ac el0t_64_sync_handler+0x68/0xbc el0_svc+0x38/0x68 do_el0_svc+0x1c/0x28 el0_svc_common+0x80/0xe0 invoke_syscall+0x58/0x114 __arm64_sys_read+0x1c/0x2c ksys_read+0x78/0xe8 vfs_read+0x1e0/0x2c8 kernfs_fop_read_iter+0x68/0x1b4 seq_read_iter+0x158/0x4ec kernfs_seq_show+0x44/0x54 sysfs_kf_seq_show+0xb4/0x130 dev_attr_show+0x38/0x74 brightness_show+0x20/0x4c dualshock4_led_get_brightness+0xc/0x74 [ 3313.874295][ T4013] Unable to handle kernel NULL pointer dereference at = virtual address 0000000000000060 [ 3313.874301][ T4013] Mem abort info: [ 3313.874303][ T4013] ESR =3D 0x0000000096000006 [ 3313.874305][ T4013] EC =3D 0x25: DABT (current EL), IL =3D 32 bits [ 3313.874307][ T4013] SET =3D 0, FnV =3D 0 [ 3313.874309][ T4013] EA =3D 0, S1PTW =3D 0 [ 3313.874311][ T4013] FSC =3D 0x06: level 2 translation fault [ 3313.874313][ T4013] Data abort info: [ 3313.874314][ T4013] ISV =3D 0, ISS =3D 0x00000006, ISS2 =3D 0x00000000 [ 3313.874316][ T4013] CM =3D 0, WnR =3D 0, TnD =3D 0, TagAccess =3D 0 [ 3313.874318][ T4013] GCS =3D 0, Overlay =3D 0, DirtyBit =3D 0, Xs =3D 0 [ 3313.874320][ T4013] user pgtable: 4k pages, 39-bit VAs, pgdp=3D00000008f= 2b0a000 .. [ 3313.874332][ T4013] Dumping ftrace buffer: [ 3313.874334][ T4013] (ftrace buffer empty) .. .. [ dd3313.874639][ T4013] CPU: 6 PID: 4013 Comm: InputReader [ 3313.874648][ T4013] pc : dualshock4_led_get_brightness+0xc/0x74 [ 3313.874653][ T4013] lr : led_update_brightness+0x38/0x60 [ 3313.874656][ T4013] sp : ffffffc0b910bbd0 .. .. [ 3313.874685][ T4013] Call trace: [ 3313.874687][ T4013] dualshock4_led_get_brightness+0xc/0x74 [ 3313.874690][ T4013] brightness_show+0x20/0x4c [ 3313.874692][ T4013] dev_attr_show+0x38/0x74 [ 3313.874696][ T4013] sysfs_kf_seq_show+0xb4/0x130 [ 3313.874700][ T4013] kernfs_seq_show+0x44/0x54 [ 3313.874703][ T4013] seq_read_iter+0x158/0x4ec [ 3313.874705][ T4013] kernfs_fop_read_iter+0x68/0x1b4 [ 3313.874708][ T4013] vfs_read+0x1e0/0x2c8 [ 3313.874711][ T4013] ksys_read+0x78/0xe8 [ 3313.874714][ T4013] __arm64_sys_read+0x1c/0x2c [ 3313.874718][ T4013] invoke_syscall+0x58/0x114 [ 3313.874721][ T4013] el0_svc_common+0x80/0xe0 [ 3313.874724][ T4013] do_el0_svc+0x1c/0x28 [ 3313.874727][ T4013] el0_svc+0x38/0x68 [ 3313.874730][ T4013] el0t_64_sync_handler+0x68/0xbc [ 3313.874732][ T4013] el0t_64_sync+0x1a8/0x1ac Signed-off-by: Mukesh Ojha reviewed-by: Anish Kumar --- Changes in v3: - s/Class/class in comment for variable led_access. Changes in v2: - Updated the comment for led_access mutex lock. - Also added mutex protection for max_brightness_show(). drivers/leds/led-class.c | 14 +++++++++++--- include/linux/leds.h | 2 +- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 06b97fd49ad9..f69f4e928d61 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -29,11 +29,14 @@ static ssize_t brightness_show(struct device *dev, struct device_attribute *attr, char *buf) { struct led_classdev *led_cdev =3D dev_get_drvdata(dev); + unsigned int brightness; =20 - /* no lock needed for this */ + mutex_lock(&led_cdev->led_access); led_update_brightness(led_cdev); + brightness =3D led_cdev->brightness; + mutex_unlock(&led_cdev->led_access); =20 - return sprintf(buf, "%u\n", led_cdev->brightness); + return sprintf(buf, "%u\n", brightness); } =20 static ssize_t brightness_store(struct device *dev, @@ -70,8 +73,13 @@ static ssize_t max_brightness_show(struct device *dev, struct device_attribute *attr, char *buf) { struct led_classdev *led_cdev =3D dev_get_drvdata(dev); + unsigned int max_brightness; + + mutex_lock(&led_cdev->led_access); + max_brightness =3D led_cdev->max_brightness; + mutex_unlock(&led_cdev->led_access); =20 - return sprintf(buf, "%u\n", led_cdev->max_brightness); + return sprintf(buf, "%u\n", max_brightness); } static DEVICE_ATTR_RO(max_brightness); =20 diff --git a/include/linux/leds.h b/include/linux/leds.h index e5968c3ed4ae..2337f516fa7c 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -238,7 +238,7 @@ struct led_classdev { struct kernfs_node *brightness_hw_changed_kn; #endif =20 - /* Ensures consistent access to the LED Flash Class device */ + /* Ensures consistent access to the LED class device */ struct mutex led_access; }; =20 --=20 2.34.1