Commit 10037421 authored by Alan Stern's avatar Alan Stern Committed by Ben Hutchings

USB: fix invalid memory access in hub_activate()

commit e50293ef upstream.

Commit 8520f380 ("USB: change hub initialization sleeps to
delayed_work") changed the hub_activate() routine to make part of it
run in a workqueue.  However, the commit failed to take a reference to
the usb_hub structure or to lock the hub interface while doing so.  As
a result, if a hub is plugged in and quickly unplugged before the work
routine can run, the routine will try to access memory that has been
deallocated.  Or, if the hub is unplugged while the routine is
running, the memory may be deallocated while it is in active use.

This patch fixes the problem by taking a reference to the usb_hub at
the start of hub_activate() and releasing it at the end (when the work
is finished), and by locking the hub interface while the work routine
is running.  It also adds a check at the start of the routine to see
if the hub has already been disconnected, in which nothing should be
done.
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Reported-by: default avatarAlexandru Cornea <alexandru.cornea@intel.com>
Tested-by: default avatarAlexandru Cornea <alexandru.cornea@intel.com>
Fixes: 8520f380 ("USB: change hub initialization sleeps to delayed_work")
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: add prototype for hub_release() before first use]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 53a68d3f
...@@ -153,7 +153,7 @@ EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem); ...@@ -153,7 +153,7 @@ EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem);
#define HUB_DEBOUNCE_STEP 25 #define HUB_DEBOUNCE_STEP 25
#define HUB_DEBOUNCE_STABLE 100 #define HUB_DEBOUNCE_STABLE 100
static void hub_release(struct kref *kref);
static int usb_reset_and_verify_device(struct usb_device *udev); static int usb_reset_and_verify_device(struct usb_device *udev);
static inline char *portspeed(struct usb_hub *hub, int portstatus) static inline char *portspeed(struct usb_hub *hub, int portstatus)
...@@ -792,10 +792,20 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) ...@@ -792,10 +792,20 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
unsigned delay; unsigned delay;
/* Continue a partial initialization */ /* Continue a partial initialization */
if (type == HUB_INIT2) if (type == HUB_INIT2 || type == HUB_INIT3) {
goto init2; device_lock(hub->intfdev);
if (type == HUB_INIT3)
/* Was the hub disconnected while we were waiting? */
if (hub->disconnected) {
device_unlock(hub->intfdev);
kref_put(&hub->kref, hub_release);
return;
}
if (type == HUB_INIT2)
goto init2;
goto init3; goto init3;
}
kref_get(&hub->kref);
/* The superspeed hub except for root hub has to use Hub Depth /* The superspeed hub except for root hub has to use Hub Depth
* value as an offset into the route string to locate the bits * value as an offset into the route string to locate the bits
...@@ -984,6 +994,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) ...@@ -984,6 +994,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func3); PREPARE_DELAYED_WORK(&hub->init_work, hub_init_func3);
schedule_delayed_work(&hub->init_work, schedule_delayed_work(&hub->init_work,
msecs_to_jiffies(delay)); msecs_to_jiffies(delay));
device_unlock(hub->intfdev);
return; /* Continues at init3: below */ return; /* Continues at init3: below */
} else { } else {
msleep(delay); msleep(delay);
...@@ -1004,6 +1015,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) ...@@ -1004,6 +1015,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
/* Allow autosuspend if it was suppressed */ /* Allow autosuspend if it was suppressed */
if (type <= HUB_INIT3) if (type <= HUB_INIT3)
usb_autopm_put_interface_async(to_usb_interface(hub->intfdev)); usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
if (type == HUB_INIT2 || type == HUB_INIT3)
device_unlock(hub->intfdev);
kref_put(&hub->kref, hub_release);
} }
/* Implement the continuations for the delays above */ /* Implement the continuations for the delays above */
......
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