From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793713418; b=fsLFnKiB9X3aycNpy90tUb+KeMV2nqk1H3UFxcDXvwl5iuMTPAdafSAHO+k0GBOw5F0g S9gWrhJ8eGemPbmtx+3/SMTKzgBbulnWWZXiYLMdp8UxPSbrjPBYKQ7VKAJcwlM20QC1b 8QIvf5QJFfsPbicDSrdE9Vavmgf1An0YOLnJaXFG3T+tO576BfUhjlf6oUx3/vwtYXdJw 0/1l0ng8rtY5MQlvpXv6gR+Z+UpdsD2tb0AEFUZFU42lyCibAcbRgj+7JlH2wvEanrh0i IhMPkBjPIwS4aEJc1pWEslOAHPqGsLwEjZTSW7W9V+tRBJZlZVChfb3YGaMZbe8pvPg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793713418; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ufthVBairYXWjpoz2GaeT0Ly5AV0s44I/BDzrNAHdLU=; b=H6+MdbKT2/jI7di0C3LF26VfFs703SRkJjCLyXgsez6lq6PGacJOV0Uzr7KC/AGDsuxF m3RySptTtrYABDVEalHAXxSLakzQrQ2tMwdv1fVD1th+6SIC4ZwAWXEiV5fI5Imeex2xQ 0PMVwdB90fEet+vQYlcqT2xSIGlrN5kHbPLJvM8E8u8K0CAw7EXco/RgyQoZ5I8oKShgM SorFC6h81yAXfrlpwXCpOTHPHGMdCQX48MVSnAs8nAqIRNRc/DcqmoH9ufhDrissmdTmy RngBI+yaoxwKeRnMG0NWutneC7paIplwgkOX5KxZ8GGFHzuI6IBtyDzlSk6gRFYLTZw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Z2Hhc0Ob; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B74D6606A326 for ; Tue, 3 Nov 2026 13:43:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Z2Hhc0Ob Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9E831F000C1; Tue, 3 Nov 2026 13:43:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793713417; bh=ufthVBairYXWjpoz2GaeT0Ly5AV0s44I/BDzrNAHdLU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Z2Hhc0ObXQrWQqGGvJMi3rbEyhqTx3MAM5cK5Fqh6ubBv+4Ey6ewUi95GeoSz6+Y1 aoyVXhia3F7GT9ljL0sSsdImexDZV8abqsyiMZxaZq2MOFQEbX2TNS9WCxQSvDeyZZ fHmNT4KRF0tdeo0zofqlPo1udEStnTSDsYVCDL2tEIzwdA5vDJJ39znOyXOx0id4sf cxv51MvTnvDrObBUnoCcvMOKDO6GspEkKzweeCO4bLl460FozwqQz6XPJshEhYkBTY 2qs4e6TkAJbME7ng2NBJIB3zuclkV4IlrX4O6nC6+vWg1INc7eLHejPWKIC2JH34ML yuDeAGWbDQ36w== From: Sasha Levin To: stable@vger.kernel.org Cc: Johan Hovold , Alan Stern , Danilo Krummrich , Sasha Levin Subject: [PATCH 6.1.y] driver core: fix parent lock use-after-free on USB disconnect Date: Tue, 3 Nov 2026 08:43:35 -0500 Message-ID: <20261103134303.3980322-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110358-trustless-overplay-52cd@gregkh> References: <2026110358-trustless-overplay-52cd@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Johan Hovold [ Upstream commit 0f554506a3fc6a21e714adf38cc3eb0ffe1bb452 ] USB interfaces should be probed with their parent USB device lock held and the USB bus therefore sets the need_parent_lock bus flag so that driver core takes the parent lock when needed. Driver core is only guaranteed to hold a reference to the parent device during initial probe however and nothing prevents the device and its parent from being deregistered and the parent potentially freed, for example, while iterating over devices in driver_attach() or bus_rescan_devices_helper(). Since commit 524134d42231 ("USB: don't cancel queued resets when unbinding drivers") USB interfaces hold a reference to their parent USB device, but a parent hub may still go away while probing a USB device (e.g. via the drivers_probe sysfs interface). This can lead to a use-after-free when taking the parent device lock before checking the device->p->dead flag of the device being probed. As only USB interfaces actually need the parent lock, make the need_parent_lock feature even more fine grained by making it a device type rather than bus feature. By requiring that any users also make sure that their devices hold a reference to their parents (like USB does), driver core can lock a device and its parent without first checking if the device has been deregistered. Note that this will also increase parallelism when using asynchronous probe as USB devices connected to the same hub can now be probed in parallel. Fixes: bf74ad5bc417 ("[PATCH] Hold the device's parent's lock during probe and remove") Cc: stable@vger.kernel.org # 2.6.16: 524134d42231: USB: don't cancel queued resets when unbinding drivers Cc: stable@vger.kernel.org # 2.6.16 Cc: Alan Stern Signed-off-by: Johan Hovold Link: https://patch.msgid.link/20261014133109.1392265-2-johan@kernel.org [ Fix mention of bus vs. device type in __device_driver_{un}lock(). - Danilo ] Signed-off-by: Danilo Krummrich [ sashal: adjusted struct bus_type context around need_parent_lock to preserve existing fields ] Signed-off-by: Sasha Levin --- drivers/base/bus.c | 4 ++-- drivers/base/dd.c | 8 ++++---- drivers/usb/core/driver.c | 1 - drivers/usb/core/message.c | 1 + include/linux/device.h | 5 +++++ include/linux/device/bus.h | 3 --- 6 files changed, 12 insertions(+), 10 deletions(-) diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 941532ddfdc68..b2d4c08848a8c 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -689,10 +689,10 @@ static int __must_check bus_rescan_devices_helper(struct device *dev, int ret = 0; if (!dev->driver) { - if (dev->parent && dev->bus->need_parent_lock) + if (dev->type && dev->type->need_parent_lock) device_lock(dev->parent); ret = device_attach(dev); - if (dev->parent && dev->bus->need_parent_lock) + if (dev->type && dev->type->need_parent_lock) device_unlock(dev->parent); } return ret < 0 ? ret : 0; diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 16f9d895ee24e..71653ce21efab 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -1086,7 +1086,7 @@ void device_initial_probe(struct device *dev) /* * __device_driver_lock - acquire locks needed to manipulate dev->drv * @dev: Device we will update driver info for - * @parent: Parent device. Needed if the bus requires parent lock + * @parent: Parent device. Needed if the device type requires parent lock * * This function will take the required locks for manipulating dev->drv. * Normally this will just be the @dev lock, but when called for a USB @@ -1094,7 +1094,7 @@ void device_initial_probe(struct device *dev) */ static void __device_driver_lock(struct device *dev, struct device *parent) { - if (parent && dev->bus->need_parent_lock) + if (dev->type && dev->type->need_parent_lock && parent) device_lock(parent); device_lock(dev); } @@ -1102,7 +1102,7 @@ static void __device_driver_lock(struct device *dev, struct device *parent) /* * __device_driver_unlock - release locks needed to manipulate dev->drv * @dev: Device we will update driver info for - * @parent: Parent device. Needed if the bus requires parent lock + * @parent: Parent device. Needed if the device type requires parent lock * * This function will release the required locks for manipulating dev->drv. * Normally this will just be the @dev lock, but when called for a @@ -1111,7 +1111,7 @@ static void __device_driver_lock(struct device *dev, struct device *parent) static void __device_driver_unlock(struct device *dev, struct device *parent) { device_unlock(dev); - if (parent && dev->bus->need_parent_lock) + if (dev->type && dev->type->need_parent_lock && parent) device_unlock(parent); } diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index 145ebfb1325af..f911e362b1811 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -2031,5 +2031,4 @@ struct bus_type usb_bus_type = { .name = "usb", .match = usb_device_match, .uevent = usb_uevent, - .need_parent_lock = true, }; diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 58046946411f1..037f90089eda4 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1915,6 +1915,7 @@ struct device_type usb_if_device_type = { .name = "usb_interface", .release = usb_release_interface, .uevent = usb_if_uevent, + .need_parent_lock = true, }; static struct usb_interface_assoc_descriptor *find_iad(struct usb_device *dev, diff --git a/include/linux/device.h b/include/linux/device.h index 0e83be1bccc44..b35162a3ab8b3 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -85,6 +85,10 @@ int subsys_virtual_register(struct bus_type *subsys, * information, equivalent to the kobj_type of a kobject. * If "name" is specified, the uevent will contain it in * the DEVTYPE variable. + * + * @need_parent_lock: When probing or removing a device of this type, + * driver core should lock the device's parent. Note that + * the device must hold a reference to its parent. */ struct device_type { const char *name; @@ -95,6 +99,7 @@ struct device_type { void (*release)(struct device *dev); const struct dev_pm_ops *pm; + bool need_parent_lock; }; /* interface for exporting device attributes */ diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index d8b29ccd07e56..05667a8e340ad 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -69,8 +69,6 @@ struct fwnode_handle; * @p: The private data of the driver core, only the driver core can * touch this. * @lock_key: Lock class key for use by the lock validator - * @need_parent_lock: When probing or removing a device on this bus, the - * device core should lock the device's parent. * * A bus is a channel between the processor and one or more devices. For the * purposes of the device model, all devices are connected via a bus, even if @@ -114,7 +112,6 @@ struct bus_type { struct subsys_private *p; struct lock_class_key lock_key; - bool need_parent_lock; }; extern int __must_check bus_register(struct bus_type *bus); -- 2.53.0