From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A35241EB5F8 for ; Tue, 2 Dec 2025 01:52:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764640334; cv=none; b=I0qzXi+gQkSZA5nbWmJZL0djeugQcQyJQTBwHhXZ12jwCgkQHtSVnYvr5gOUUaAe3Wr+RyK3bv1hntM+SQYMaCbHqRKvfMsXHJGEIpBFdarpknht2Gymb+dM9z2qCXDsf6Px58YQ4pl8a6ReWCbrN7Qr9+Pio58ZO8Is/rD+2nQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764640334; c=relaxed/simple; bh=939m9fXaIZwe7N3TEzYhEYBXpOO2UasgNy5j8z3oE+Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RZPilm2AdCGdV3y7I+S5erl3fL9oBZIPyssgx9HYC9m96t/NHU/swDl6a9zCSDvdUTbFy7ow+6yUdnRkmI8ODiEkefRLfdbIcRqMKWLqJopNZ6MszG+nC0ZBFXaGq4Xct+cmJ1qt47S/XTiPc6YoQ3efoT6vZMKlNCT6azGo+Yg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fZkqTDIi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fZkqTDIi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E722C19421; Tue, 2 Dec 2025 01:52:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764640334; bh=939m9fXaIZwe7N3TEzYhEYBXpOO2UasgNy5j8z3oE+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fZkqTDIimF43Yr8IADeyFIis2lFb6DYxmyfoHaCkjAyVsQkTaf5fTJM0HOIwltQPn 2G16fZBPgVv8vSn62jmJxzAe8VmCW+CGt+X9vWfGsssgM1wZ9gs4YQsx66JGFKYAG7 7VHdWIb+gNFa8dwMBMpRTa7Zwqa8ZmtJAXy7EZDm+6ugHgjvVldHM7N6qQfvi9Hn0g qpy34ytx8gcTeqZ+QoF5BSYn4AFvqvcc+hLmmwFYOo5ZZkuI7LaU471SdQMnAvkfNk znk/OHDwLdsSjEwscAYY//FPAO2xmIsnLNVLaYwp9JoD3cEdh2XYl9I8JvO+vDnMT5 xjOdo9phnDCBw== From: Sasha Levin To: stable@vger.kernel.org Cc: Jimmy Hu , stable , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y 2/2] usb: gadget: udc: fix use-after-free in usb_gadget_state_work Date: Mon, 1 Dec 2025 20:52:09 -0500 Message-ID: <20251202015209.1607256-2-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251202015209.1607256-1-sashal@kernel.org> References: <2025120121-sift-shiny-dd51@gregkh> <20251202015209.1607256-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jimmy Hu [ Upstream commit baeb66fbd4201d1c4325074e78b1f557dff89b5b ] A race condition during gadget teardown can lead to a use-after-free in usb_gadget_state_work(), as reported by KASAN: BUG: KASAN: invalid-access in sysfs_notify+0x2c/0xd0 Workqueue: events usb_gadget_state_work The fundamental race occurs because a concurrent event (e.g., an interrupt) can call usb_gadget_set_state() and schedule gadget->work at any time during the cleanup process in usb_del_gadget(). Commit 399a45e5237c ("usb: gadget: core: flush gadget workqueue after device removal") attempted to fix this by moving flush_work() to after device_del(). However, this does not fully solve the race, as a new work item can still be scheduled *after* flush_work() completes but before the gadget's memory is freed, leading to the same use-after-free. This patch fixes the race condition robustly by introducing a 'teardown' flag and a 'state_lock' spinlock to the usb_gadget struct. The flag is set during cleanup in usb_del_gadget() *before* calling flush_work() to prevent any new work from being scheduled once cleanup has commenced. The scheduling site, usb_gadget_set_state(), now checks this flag under the lock before queueing the work, thus safely closing the race window. Fixes: 5702f75375aa9 ("usb: gadget: udc-core: move sysfs_notify() to a workqueue") Cc: stable Signed-off-by: Jimmy Hu Link: https://patch.msgid.link/20251023054945.233861-1-hhhuuu@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/gadget/udc/core.c | 17 ++++++++++++++++- include/linux/usb/gadget.h | 5 +++++ 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 694653761c44c..8dbe79bdc0f9c 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -1126,8 +1126,13 @@ static void usb_gadget_state_work(struct work_struct *work) void usb_gadget_set_state(struct usb_gadget *gadget, enum usb_device_state state) { + unsigned long flags; + + spin_lock_irqsave(&gadget->state_lock, flags); gadget->state = state; - schedule_work(&gadget->work); + if (!gadget->teardown) + schedule_work(&gadget->work); + spin_unlock_irqrestore(&gadget->state_lock, flags); trace_usb_gadget_set_state(gadget, 0); } EXPORT_SYMBOL_GPL(usb_gadget_set_state); @@ -1361,6 +1366,8 @@ static void usb_udc_nop_release(struct device *dev) void usb_initialize_gadget(struct device *parent, struct usb_gadget *gadget, void (*release)(struct device *dev)) { + spin_lock_init(&gadget->state_lock); + gadget->teardown = false; INIT_WORK(&gadget->work, usb_gadget_state_work); gadget->dev.parent = parent; @@ -1535,6 +1542,7 @@ EXPORT_SYMBOL_GPL(usb_add_gadget_udc); void usb_del_gadget(struct usb_gadget *gadget) { struct usb_udc *udc = gadget->udc; + unsigned long flags; if (!udc) return; @@ -1548,6 +1556,13 @@ void usb_del_gadget(struct usb_gadget *gadget) kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE); sysfs_remove_link(&udc->dev.kobj, "gadget"); device_del(&gadget->dev); + /* + * Set the teardown flag before flushing the work to prevent new work + * from being scheduled while we are cleaning up. + */ + spin_lock_irqsave(&gadget->state_lock, flags); + gadget->teardown = true; + spin_unlock_irqrestore(&gadget->state_lock, flags); flush_work(&gadget->work); ida_free(&gadget_id_numbers, gadget->id_number); cancel_work_sync(&udc->vbus_work); diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index da4309f3cea3f..b5d9a1d91e39e 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -376,6 +376,9 @@ struct usb_gadget_ops { * can handle. The UDC must support this and all slower speeds and lower * number of lanes. * @state: the state we are now (attached, suspended, configured, etc) + * @state_lock: Spinlock protecting the `state` and `teardown` members. + * @teardown: True if the device is undergoing teardown, used to prevent + * new work from being scheduled during cleanup. * @name: Identifies the controller hardware type. Used in diagnostics * and sometimes configuration. * @dev: Driver model state for this abstract device. @@ -451,6 +454,8 @@ struct usb_gadget { enum usb_ssp_rate max_ssp_rate; enum usb_device_state state; + spinlock_t state_lock; + bool teardown; const char *name; struct device dev; unsigned isoch_delay; -- 2.51.0