From 31604075ceb49366fbd2f50aa8dd7135a773b61b Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 9 Oct 2019 19:09:42 +0200 Subject: [PATCH] USB: usb-skeleton: fix NULL-deref on disconnect commit bed5ef230943863b9abf5eae226a20fad9a8ff71 upstream. 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 Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20191009170944.30057-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- 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 85b01f1..e0cf11f 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -59,6 +59,7 @@ 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) @@ -236,7 +237,7 @@ 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; } @@ -418,7 +419,7 @@ 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; @@ -569,7 +570,7 @@ 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); -- 2.7.4