The driver was using its struct usb_interface pointer as an inverted
disconnected flag and was setting it to NULL before making sure all
completion handlers had run. This could lead to NULL-pointer
dereferences in the dev_err() statements in the completion handlers
which relies on said pointer.
Fix this by using a dedicated disconnected flag.
Note that this is also addresses a NULL-pointer dereference at release()
and a struct usb_interface reference leak introduced by a recent runtime
PM fix, which depends on and should have been submitted together with
this patch.
Fixes: 4212cd74ca6f ("USB: usb-skeleton.c: remove err() usage")
Fixes: 5c290a5e42c3 ("USB: usb-skeleton: fix runtime PM after driver unbind")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/usb/usb-skeleton.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 8001d6384c73..c2843fcfa52d 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -61,6 +61,7 @@ struct usb_skel {
spinlock_t err_lock; /* lock for errors */
struct kref kref;
struct mutex io_mutex; /* synchronize I/O with disconnect */
+ unsigned long disconnected:1;
wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
};
#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
@@ -238,7 +239,7 @@ static ssize_t skel_read(struct file *file, char *buffer, size_t count,
if (rv < 0)
return rv;
- if (!dev->interface) { /* disconnect() was called */
+ if (dev->disconnected) { /* disconnect() was called */
rv = -ENODEV;
goto exit;
}
@@ -420,7 +421,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer,
/* this lock makes sure we don't submit URBs to gone devices */
mutex_lock(&dev->io_mutex);
- if (!dev->interface) { /* disconnect() was called */
+ if (dev->disconnected) { /* disconnect() was called */
mutex_unlock(&dev->io_mutex);
retval = -ENODEV;
goto error;
@@ -571,7 +572,7 @@ static void skel_disconnect(struct usb_interface *interface)
/* prevent more I/O from starting */
mutex_lock(&dev->io_mutex);
- dev->interface = NULL;
+ dev->disconnected = 1;
mutex_unlock(&dev->io_mutex);
usb_kill_anchored_urbs(&dev->submitted);
--
2.23.0
