[PATCH AUTOSEL 6.1 10/26] usb: core: stop USB enumeration if too many retries

Sasha Levin
2022-12-24T01:31:04Z

From: Ray Chi <raychi@google.com>

[ Upstream commit 430d57f53eb1cdbf9ba9bbd397317912b3cd2de5 ]

When a broken USB accessory connects to a USB host, usbcore might
keep doing enumeration retries. If the host has a watchdog mechanism,
the kernel panic will happen on the host.

This patch provides an attribute early_stop to limit the numbers of retries
for each port of a hub. If a port was marked with early_stop attribute,
unsuccessful connection attempts will fail quickly. In addition, if an
early_stop port has failed to initialize, it will ignore all future
connection events until early_stop attribute is clear.

Signed-off-by: Ray Chi <raychi@google.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20221107072754.3336357-1-raychi@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
Documentation/ABI/testing/sysfs-bus-usb | 11 +++++
drivers/usb/core/hub.c | 60 +++++++++++++++++++++++++
drivers/usb/core/hub.h | 4 ++
drivers/usb/core/port.c | 27 +++++++++++
4 files changed, 102 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 568103d3376e..545c2dd97ed0 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -264,6 +264,17 @@ Description:
attached to the port will not be detected, initialized,
or enumerated.

+What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop
+Date: Sep 2022
+Contact: Ray Chi <raychi@google.com>
+Description:
+ Some USB hosts have some watchdog mechanisms so that the device
+ may enter ramdump if it takes a long time during port initialization.
+ This attribute allows each port just has two attempts so that the
+ port initialization will be failed quickly. In addition, if a port
+ which is marked with early_stop has failed to initialize, it will ignore
+ all future connections until this attribute is clear.
+
What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
Date: May 2013
Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bbab424b0d55..77e73fc8d673 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3081,6 +3081,48 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
return status;
}

+/*
+ * hub_port_stop_enumerate - stop USB enumeration or ignore port events
+ * @hub: target hub
+ * @port1: port num of the port
+ * @retries: port retries number of hub_port_init()
+ *
+ * Return:
+ * true: ignore port actions/events or give up connection attempts.
+ * false: keep original behavior.
+ *
+ * This function will be based on retries to check whether the port which is
+ * marked with early_stop attribute would stop enumeration or ignore events.
+ *
+ * Note:
+ * This function didn't change anything if early_stop is not set, and it will
+ * prevent all connection attempts when early_stop is set and the attempts of
+ * the port are more than 1.
+ */
+static bool hub_port_stop_enumerate(struct usb_hub *hub, int port1, int retries)
+{
+ struct usb_port *port_dev = hub->ports[port1 - 1];
+
+ if (port_dev->early_stop) {
+ if (port_dev->ignore_event)
+ return true;
+
+ /*
+ * We want unsuccessful attempts to fail quickly.
+ * Since some devices may need one failure during
+ * port initialization, we allow two tries but no
+ * more.
+ */
+ if (retries < 2)
+ return false;
+
+ port_dev->ignore_event = 1;
+ } else
+ port_dev->ignore_event = 0;
+
+ return port_dev->ignore_event;
+}
+
/* Check if a port is power on */
int usb_port_is_power_on(struct usb_hub *hub, unsigned int portstatus)
{
@@ -4796,6 +4838,11 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
do_new_scheme = use_new_scheme(udev, retry_counter, port_dev);

for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
+ if (hub_port_stop_enumerate(hub, port1, retries)) {
+ retval = -ENODEV;
+ break;
+ }
+
if (do_new_scheme) {
struct usb_device_descriptor *buf;
int r = 0;
@@ -5246,6 +5293,11 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
status = 0;

for (i = 0; i < PORT_INIT_TRIES; i++) {
+ if (hub_port_stop_enumerate(hub, port1, i)) {
+ status = -ENODEV;
+ break;
+ }
+
usb_lock_port(port_dev);
mutex_lock(hcd->address0_mutex);
retry_locked = true;
@@ -5614,6 +5666,10 @@ static void port_event(struct usb_hub *hub, int port1)
if (!pm_runtime_active(&port_dev->dev))
return;

+ /* skip port actions if ignore_event and early_stop are true */
+ if (port_dev->ignore_event && port_dev->early_stop)
+ return;
+
if (hub_handle_remote_wakeup(hub, port1, portstatus, portchange))
connect_change = 1;

@@ -5927,6 +5983,10 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
mutex_lock(hcd->address0_mutex);

for (i = 0; i < PORT_INIT_TRIES; ++i) {
+ if (hub_port_stop_enumerate(parent_hub, port1, i)) {
+ ret = -ENODEV;
+ break;
+ }

/* ep0 maxpacket size may change; let the HCD know about it.
* Other endpoints will be handled by re-enumeration. */
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index b2925856b4cb..e23833562e4f 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -90,6 +90,8 @@ struct usb_hub {
* @is_superspeed cache super-speed status
* @usb3_lpm_u1_permit: whether USB3 U1 LPM is permitted.
* @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted.
+ * @early_stop: whether port initialization will be stopped earlier.
+ * @ignore_event: whether events of the port are ignored.
*/
struct usb_port {
struct usb_device *child;
@@ -103,6 +105,8 @@ struct usb_port {
u32 over_current_count;
u8 portnum;
u32 quirks;
+ unsigned int early_stop:1;
+ unsigned int ignore_event:1;
unsigned int is_superspeed:1;
unsigned int usb3_lpm_u1_permit:1;
unsigned int usb3_lpm_u2_permit:1;
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 38c1a4f4fdea..126da9408359 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -17,6 +17,32 @@ static int usb_port_block_power_off;

static const struct attribute_group *port_dev_group[];

+static ssize_t early_stop_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct usb_port *port_dev = to_usb_port(dev);
+
+ return sysfs_emit(buf, "%s\n", port_dev->early_stop ? "yes" : "no");
+}
+
+static ssize_t early_stop_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct usb_port *port_dev = to_usb_port(dev);
+ bool value;
+
+ if (kstrtobool(buf, &value))
+ return -EINVAL;
+
+ if (value)
+ port_dev->early_stop = 1;
+ else
+ port_dev->early_stop = 0;
+
+ return count;
+}
+static DEVICE_ATTR_RW(early_stop);
+
static ssize_t disable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -236,6 +262,7 @@ static struct attribute *port_dev_attrs[] = {
&dev_attr_quirks.attr,
&dev_attr_over_current_count.attr,
&dev_attr_disable.attr,
+ &dev_attr_early_stop.attr,
NULL,
};

--
2.35.1