This is a note to let you know that I've just added the patch titled
usb: gadget: udc: core: Prevent soft_connect_store() race
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-udc-core-prevent-soft_connect_store-race.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 286d9975a838d0a54da049765fa1d1fb96b89682 Mon Sep 17 00:00:00 2001
From: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
Date: Fri, 9 Jun 2023 01:02:27 +0000
Subject: usb: gadget: udc: core: Prevent soft_connect_store() race
From: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
commit 286d9975a838d0a54da049765fa1d1fb96b89682 upstream.
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@xxxxxxxxxxxxxxxxxxxxxxxxxxxx/.
commit 16737e78d190 ("usb: gadget: udc: core: Offload usb_udc_vbus_handler processing")
addresses the crash reported.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler")
Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>
Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Message-ID: <20230609010227.978661-2-badhri@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/udc/core.c | 155 ++++++++++++++++++++++++++++--------------
1 file changed, 106 insertions(+), 49 deletions(-)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -40,6 +40,11 @@ static 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;
@@ -665,17 +671,8 @@ out:
}
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;
@@ -684,10 +681,12 @@ int usb_gadget_connect(struct usb_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;
@@ -702,22 +701,31 @@ out:
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;
@@ -729,7 +737,7 @@ int usb_gadget_disconnect(struct usb_gad
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.
@@ -752,6 +760,30 @@ out:
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);
/**
@@ -769,13 +801,14 @@ int usb_gadget_deactivate(struct usb_gad
{
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
@@ -785,7 +818,8 @@ int usb_gadget_deactivate(struct usb_gad
}
gadget->deactivated = true;
-out:
+unlock:
+ mutex_unlock(&gadget->udc->connect_lock);
trace_usb_gadget_deactivate(gadget, ret);
return ret;
@@ -805,8 +839,9 @@ int usb_gadget_activate(struct usb_gadge
{
int ret = 0;
+ mutex_lock(&gadget->udc->connect_lock);
if (!gadget->deactivated)
- goto out;
+ goto unlock;
gadget->deactivated = false;
@@ -815,9 +850,11 @@ int usb_gadget_activate(struct usb_gadge
* 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);
-out:
+unlock:
+ mutex_unlock(&gadget->udc->connect_lock);
trace_usb_gadget_activate(gadget, ret);
return ret;
@@ -1056,19 +1093,22 @@ 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);
}
/**
@@ -1117,7 +1157,7 @@ void usb_gadget_udc_reset(struct usb_gad
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
@@ -1128,8 +1168,11 @@ 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;
@@ -1146,7 +1189,7 @@ static inline int usb_gadget_udc_start(s
}
/**
- * 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
@@ -1155,8 +1198,11 @@ static inline int usb_gadget_udc_start(s
* 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");
@@ -1315,6 +1361,7 @@ int usb_add_gadget(struct usb_gadget *ga
udc->gadget = gadget;
gadget->udc = udc;
+ mutex_init(&udc->connect_lock);
udc->started = false;
@@ -1518,12 +1565,16 @@ static int gadget_bind_driver(struct 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;
@@ -1556,12 +1607,14 @@ static void gadget_unbind_driver(struct
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;
@@ -1647,11 +1700,15 @@ static ssize_t soft_connect_store(struct
}
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;
Patches currently in stable-queue which might be from badhri@xxxxxxxxxx are
queue-6.3/usb-gadget-udc-core-offload-usb_udc_vbus_handler-processing.patch
queue-6.3/usb-gadget-udc-core-prevent-soft_connect_store-race.patch
