From patchwork Thu Jun 8 20:45:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Badhri Jagan Sridharan X-Patchwork-Id: 691095 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 8B97DC7EE43 for ; Thu, 8 Jun 2023 20:45:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236236AbjFHUpb (ORCPT ); Thu, 8 Jun 2023 16:45:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236399AbjFHUpZ (ORCPT ); Thu, 8 Jun 2023 16:45:25 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3D2F2D78 for ; Thu, 8 Jun 2023 13:45:23 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id 41be03b00d2f7-53f06f7cc74so37767a12.1 for ; Thu, 08 Jun 2023 13:45:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686257123; x=1688849123; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=9En/nA5czqY9XvtbArZPF0a5d5bx2uzrlb5JXAauKEk=; b=LcZUFeGLOqh8MsfZjy7K8UJmsHg7DfXznBT8pgXg5TLU8u+JfUaAlaVJJngJ82Isgj fUqBOStw4LzgA3u/GDqushb3hKz7EOPXyaOyuxgCILe2i97ybRjZ3+8LzjTNZf6QBfxG sdc6ABcuaE/A9VDeL733eu4QZGdOGn3KPgjfLpk2uv5WlaoWba2hNf934LfljlGzg78J JWCbdombtt3ka9BRe9IoXvrx6tXKw0OcrEiWlPz8kahkOu5+loLmjazWuOECM23o+8SB L1zToRLAF7T/vbuCzWiFOEW4by1Jv1Z67S9eZbq+dAnZYvph0fIWHpY4s03JfOpF4BAK CcdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686257123; x=1688849123; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9En/nA5czqY9XvtbArZPF0a5d5bx2uzrlb5JXAauKEk=; b=JdKQHq3h+7Dmz8bki1wFWCn6X3eeLLd4UVKfaxvhLIp6w0PQnlpMavE0B9ZJC2/L10 NQKCGsLOdSdrOoT2dZnupcjbcCwNz2Svj3kd+4BxPwq4qgEwUVzqD8TNvuI8e4XU8r1O 307sqLwnCDlvHMLM6+ZmwIhsiGAYbvIdHJ0hPGrmzAAVP0p3yBCHWo6SpPvj4aY/K/x6 6eN/DgDbxOya1XWlc+BxmBILBse4ecgNuDMtSbkc0OFN0W4WWzWV4Lv45vXoXXDHBXEn sdIKv6F2lgL7nkkKd0FWEo5UC366AUSvtP6G+0p9WbB+RE33kA9HznjAjp+nit2q3soA 6yEQ== X-Gm-Message-State: AC+VfDwAF9Le8YB06BugC+5NPe7tb4dh350r0PSr4/UJe+f6icTSVXK2 6YFoD2DvmLsvMl6ZkozdefP9k9ORZR0= X-Google-Smtp-Source: ACHHUZ6ZL4e+KQm5hk9ItwvAyYFHrFQaEiVNmL5bpvK1eBLv3iLaBs2yBEp898ky+qy8yFSJVo+/ks6sKJ4= X-Received: from badhri.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:6442]) (user=badhri job=sendgmr) by 2002:a63:1e64:0:b0:520:77f8:a145 with SMTP id p36-20020a631e64000000b0052077f8a145mr132138pgm.5.1686257123114; Thu, 08 Jun 2023 13:45:23 -0700 (PDT) Date: Thu, 8 Jun 2023 20:45:16 +0000 In-Reply-To: <20230608204517.105396-1-badhri@google.com> Mime-Version: 1.0 References: <20230608204517.105396-1-badhri@google.com> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230608204517.105396-2-badhri@google.com> Subject: [PATCH v7 2/2] usb: gadget: udc: core: Prevent soft_connect_store() race From: Badhri Jagan Sridharan To: gregkh@linuxfoundation.org, stern@rowland.harvard.edu, colin.i.king@gmail.com, xuetao09@huawei.com, quic_eserrao@quicinc.com, water.zhangjiantao@huawei.com, peter.chen@freescale.com, balbi@ti.com, francesco@dolcini.it, alistair@alistair23.me, stephan@gerhold.net, bagasdotme@gmail.com, luca@z3ntu.xyz Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Badhri Jagan Sridharan Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org usb_udc_connect_control(), soft_connect_store() and usb_gadget_deactivate() can potentially race against each other to invoke usb_gadget_connect()/usb_gadget_disconnect(). To prevent this, guard udc->started, gadget->allow_connect, gadget->deactivate and gadget->connect with connect_lock so that ->pullup() is only invoked when the gadget is bound, started and not deactivated. The routines usb_gadget_connect_locked(), usb_gadget_disconnect_locked(), usb_udc_connect_control_locked(), usb_gadget_udc_start_locked(), usb_gadget_udc_stop_locked() are called with this lock held. An earlier version of this commit was reverted due to the crash reported in https://lore.kernel.org/all/ZF4BvgsOyoKxdPFF@francesco-nb.int.toradex.com/. commit 16737e78d190 ("usb: gadget: udc: core: Offload usb_udc_vbus_handler processing") addresses the crash reported. Cc: stable@vger.kernel.org Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler") Signed-off-by: Badhri Jagan Sridharan --- v5 is the first version in this series. Changes since v5: ** Fixed up commit message ** Wrapped comments at 76. Changes since v6: ** Address Alan comments around style/presentation. ** Fixed code to acquire ->connect_lock before testing gadget->deactivated. --- drivers/usb/gadget/udc/core.c | 153 +++++++++++++++++++++++----------- 1 file changed, 106 insertions(+), 47 deletions(-) diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index d2e4f78c53e3..2549717c1446 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -40,6 +40,11 @@ static const struct bus_type gadget_bus_type; * @allow_connect: Indicates whether UDC is allowed to be pulled up. * Set/cleared by gadget_(un)bind_driver() after gadget driver is bound or * unbound. + * @connect_lock: protects udc->started, gadget->connect, + * gadget->allow_connect and gadget->deactivate. The routines + * usb_gadget_connect_locked(), usb_gadget_disconnect_locked(), + * usb_udc_connect_control_locked(), usb_gadget_udc_start_locked() and + * usb_gadget_udc_stop_locked() are called with this lock held. * * This represents the internal data structure which is used by the UDC-class * to hold information about udc driver and gadget together. @@ -53,6 +58,7 @@ struct usb_udc { bool started; bool allow_connect; struct work_struct vbus_work; + struct mutex connect_lock; }; static struct class *udc_class; @@ -692,17 +698,8 @@ int usb_gadget_vbus_disconnect(struct usb_gadget *gadget) } EXPORT_SYMBOL_GPL(usb_gadget_vbus_disconnect); -/** - * usb_gadget_connect - software-controlled connect to USB host - * @gadget:the peripheral being connected - * - * Enables the D+ (or potentially D-) pullup. The host will start - * enumerating this gadget when the pullup is active and a VBUS session - * is active (the link is powered). - * - * Returns zero on success, else negative errno. - */ -int usb_gadget_connect(struct usb_gadget *gadget) +static int usb_gadget_connect_locked(struct usb_gadget *gadget) + __must_hold(&gadget->udc->connect_lock) { int ret = 0; @@ -711,10 +708,12 @@ int usb_gadget_connect(struct usb_gadget *gadget) goto out; } - if (gadget->deactivated || !gadget->udc->allow_connect) { + if (gadget->deactivated || !gadget->udc->allow_connect || !gadget->udc->started) { /* - * If gadget is deactivated we only save new state. - * Gadget will be connected automatically after activation. + * If the gadget isn't usable (because it is deactivated, + * unbound, or not yet started), we only save the new state. + * The gadget will be connected automatically when it is + * activated/bound/started. */ gadget->connected = true; goto out; @@ -729,22 +728,31 @@ int usb_gadget_connect(struct usb_gadget *gadget) return ret; } -EXPORT_SYMBOL_GPL(usb_gadget_connect); /** - * usb_gadget_disconnect - software-controlled disconnect from USB host - * @gadget:the peripheral being disconnected - * - * Disables the D+ (or potentially D-) pullup, which the host may see - * as a disconnect (when a VBUS session is active). Not all systems - * support software pullup controls. + * usb_gadget_connect - software-controlled connect to USB host + * @gadget:the peripheral being connected * - * Following a successful disconnect, invoke the ->disconnect() callback - * for the current gadget driver so that UDC drivers don't need to. + * Enables the D+ (or potentially D-) pullup. The host will start + * enumerating this gadget when the pullup is active and a VBUS session + * is active (the link is powered). * * Returns zero on success, else negative errno. */ -int usb_gadget_disconnect(struct usb_gadget *gadget) +int usb_gadget_connect(struct usb_gadget *gadget) +{ + int ret; + + mutex_lock(&gadget->udc->connect_lock); + ret = usb_gadget_connect_locked(gadget); + mutex_unlock(&gadget->udc->connect_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(usb_gadget_connect); + +static int usb_gadget_disconnect_locked(struct usb_gadget *gadget) + __must_hold(&gadget->udc->connect_lock) { int ret = 0; @@ -756,7 +764,7 @@ int usb_gadget_disconnect(struct usb_gadget *gadget) if (!gadget->connected) goto out; - if (gadget->deactivated) { + if (gadget->deactivated || !gadget->udc->started) { /* * If gadget is deactivated we only save new state. * Gadget will stay disconnected after activation. @@ -779,6 +787,30 @@ int usb_gadget_disconnect(struct usb_gadget *gadget) return ret; } + +/** + * usb_gadget_disconnect - software-controlled disconnect from USB host + * @gadget:the peripheral being disconnected + * + * Disables the D+ (or potentially D-) pullup, which the host may see + * as a disconnect (when a VBUS session is active). Not all systems + * support software pullup controls. + * + * Following a successful disconnect, invoke the ->disconnect() callback + * for the current gadget driver so that UDC drivers don't need to. + * + * Returns zero on success, else negative errno. + */ +int usb_gadget_disconnect(struct usb_gadget *gadget) +{ + int ret; + + mutex_lock(&gadget->udc->connect_lock); + ret = usb_gadget_disconnect_locked(gadget); + mutex_unlock(&gadget->udc->connect_lock); + + return ret; +} EXPORT_SYMBOL_GPL(usb_gadget_disconnect); /** @@ -796,13 +828,14 @@ int usb_gadget_deactivate(struct usb_gadget *gadget) { int ret = 0; + mutex_lock(&gadget->udc->connect_lock); if (gadget->deactivated) - goto out; + goto unlock; if (gadget->connected) { - ret = usb_gadget_disconnect(gadget); + ret = usb_gadget_disconnect_locked(gadget); if (ret) - goto out; + goto unlock; /* * If gadget was being connected before deactivation, we want @@ -812,6 +845,8 @@ int usb_gadget_deactivate(struct usb_gadget *gadget) } gadget->deactivated = true; +unlock: + mutex_unlock(&gadget->udc->connect_lock); out: trace_usb_gadget_deactivate(gadget, ret); @@ -832,8 +867,9 @@ int usb_gadget_activate(struct usb_gadget *gadget) { int ret = 0; + mutex_lock(&gadget->udc->connect_lock); if (!gadget->deactivated) - goto out; + goto unlock; gadget->deactivated = false; @@ -842,8 +878,11 @@ int usb_gadget_activate(struct usb_gadget *gadget) * while it was being deactivated, we call usb_gadget_connect(). */ if (gadget->connected) - ret = usb_gadget_connect(gadget); + ret = usb_gadget_connect_locked(gadget); + mutex_unlock(&gadget->udc->connect_lock); +unlock: + mutex_unlock(&gadget->udc->connect_lock); out: trace_usb_gadget_activate(gadget, ret); @@ -1083,19 +1122,22 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state); /* ------------------------------------------------------------------------- */ -static void usb_udc_connect_control(struct usb_udc *udc) +/* Acquire connect_lock before calling this function. */ +static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock) { if (udc->vbus) - usb_gadget_connect(udc->gadget); + usb_gadget_connect_locked(udc->gadget); else - usb_gadget_disconnect(udc->gadget); + usb_gadget_disconnect_locked(udc->gadget); } static void vbus_event_work(struct work_struct *work) { struct usb_udc *udc = container_of(work, struct usb_udc, vbus_work); - usb_udc_connect_control(udc); + mutex_lock(&udc->connect_lock); + usb_udc_connect_control_locked(udc); + mutex_unlock(&udc->connect_lock); } /** @@ -1144,7 +1186,7 @@ void usb_gadget_udc_reset(struct usb_gadget *gadget, EXPORT_SYMBOL_GPL(usb_gadget_udc_reset); /** - * usb_gadget_udc_start - tells usb device controller to start up + * usb_gadget_udc_start_locked - tells usb device controller to start up * @udc: The UDC to be started * * This call is issued by the UDC Class driver when it's about @@ -1155,8 +1197,11 @@ EXPORT_SYMBOL_GPL(usb_gadget_udc_reset); * necessary to have it powered on. * * Returns zero on success, else negative errno. + * + * Caller should acquire connect_lock before invoking this function. */ -static inline int usb_gadget_udc_start(struct usb_udc *udc) +static inline int usb_gadget_udc_start_locked(struct usb_udc *udc) + __must_hold(&udc->connect_lock) { int ret; @@ -1173,7 +1218,7 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc) } /** - * usb_gadget_udc_stop - tells usb device controller we don't need it anymore + * usb_gadget_udc_stop_locked - tells usb device controller we don't need it anymore * @udc: The UDC to be stopped * * This call is issued by the UDC Class driver after calling @@ -1182,8 +1227,11 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc) * The details are implementation specific, but it can go as * far as powering off UDC completely and disable its data * line pullups. + * + * Caller should acquire connect lock before invoking this function. */ -static inline void usb_gadget_udc_stop(struct usb_udc *udc) +static inline void usb_gadget_udc_stop_locked(struct usb_udc *udc) + __must_hold(&udc->connect_lock) { if (!udc->started) { dev_err(&udc->dev, "UDC had already stopped\n"); @@ -1342,6 +1390,7 @@ int usb_add_gadget(struct usb_gadget *gadget) udc->gadget = gadget; gadget->udc = udc; + mutex_init(&udc->connect_lock); udc->started = false; @@ -1545,12 +1594,16 @@ static int gadget_bind_driver(struct device *dev) if (ret) goto err_bind; - ret = usb_gadget_udc_start(udc); - if (ret) + mutex_lock(&udc->connect_lock); + ret = usb_gadget_udc_start_locked(udc); + if (ret) { + mutex_unlock(&udc->connect_lock); goto err_start; + } usb_gadget_enable_async_callbacks(udc); udc->allow_connect = true; - usb_udc_connect_control(udc); + usb_udc_connect_control_locked(udc); + mutex_unlock(&udc->connect_lock); kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); return 0; @@ -1583,12 +1636,14 @@ static void gadget_unbind_driver(struct device *dev) udc->allow_connect = false; cancel_work_sync(&udc->vbus_work); - usb_gadget_disconnect(gadget); + mutex_lock(&udc->connect_lock); + usb_gadget_disconnect_locked(gadget); usb_gadget_disable_async_callbacks(udc); if (gadget->irq) synchronize_irq(gadget->irq); udc->driver->unbind(gadget); - usb_gadget_udc_stop(udc); + usb_gadget_udc_stop_locked(udc); + mutex_unlock(&udc->connect_lock); mutex_lock(&udc_lock); driver->is_bound = false; @@ -1674,11 +1729,15 @@ static ssize_t soft_connect_store(struct device *dev, } if (sysfs_streq(buf, "connect")) { - usb_gadget_udc_start(udc); - usb_gadget_connect(udc->gadget); + mutex_lock(&udc->connect_lock); + usb_gadget_udc_start_locked(udc); + usb_gadget_connect_locked(udc->gadget); + mutex_unlock(&udc->connect_lock); } else if (sysfs_streq(buf, "disconnect")) { - usb_gadget_disconnect(udc->gadget); - usb_gadget_udc_stop(udc); + mutex_lock(&udc->connect_lock); + usb_gadget_disconnect_locked(udc->gadget); + usb_gadget_udc_stop_locked(udc); + mutex_unlock(&udc->connect_lock); } else { dev_err(dev, "unsupported command '%s'\n", buf); ret = -EINVAL;