This is a note to let you know that I've just added the patch titled
USB: yurex: fix NULL-derefs on disconnect
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From aafb00a977cf7d81821f7c9d12e04c558c22dc3c Mon Sep 17 00:00:00 2001
From: Johan Hovold johan@kernel.org Date: Wed, 9 Oct 2019 17:38:48 +0200 Subject: USB: yurex: fix NULL-derefs on disconnect
The driver was using its struct usb_interface pointer as an inverted disconnected flag, but was setting it to NULL without making sure all code paths that used it were done with it.
Before commit ef61eb43ada6 ("USB: yurex: Fix protection fault after device removal") this included the interrupt-in completion handler, but there are further accesses in dev_err and dev_dbg statements in yurex_write() and the driver-data destructor (sic!).
Fix this by unconditionally stopping also the control URB at disconnect and by using a dedicated disconnected flag.
Note that we need to take a reference to the struct usb_interface to avoid a use-after-free in the destructor whenever the device was disconnected while the character device was still open.
Fixes: aadd6472d904 ("USB: yurex.c: remove dbg() usage") Fixes: 45714104b9e8 ("USB: yurex.c: remove err() usage") Cc: stable stable@vger.kernel.org # 3.5: ef61eb43ada6 Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20191009153848.8664-6-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/misc/yurex.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 8d52d4336c29..be0505b8b5d4 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -60,6 +60,7 @@ struct usb_yurex {
struct kref kref; struct mutex io_mutex; + unsigned long disconnected:1; struct fasync_struct *async_queue; wait_queue_head_t waitq;
@@ -107,6 +108,7 @@ static void yurex_delete(struct kref *kref) dev->int_buffer, dev->urb->transfer_dma); usb_free_urb(dev->urb); } + usb_put_intf(dev->interface); usb_put_dev(dev->udev); kfree(dev); } @@ -205,7 +207,7 @@ static int yurex_probe(struct usb_interface *interface, const struct usb_device_ init_waitqueue_head(&dev->waitq);
dev->udev = usb_get_dev(interface_to_usbdev(interface)); - dev->interface = interface; + dev->interface = usb_get_intf(interface);
/* set up the endpoint information */ iface_desc = interface->cur_altsetting; @@ -316,8 +318,9 @@ static void yurex_disconnect(struct usb_interface *interface)
/* prevent more I/O from starting */ usb_poison_urb(dev->urb); + usb_poison_urb(dev->cntl_urb); mutex_lock(&dev->io_mutex); - dev->interface = NULL; + dev->disconnected = 1; mutex_unlock(&dev->io_mutex);
/* wakeup waiters */ @@ -405,7 +408,7 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, dev = file->private_data;
mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* already disconnected */ + if (dev->disconnected) { /* already disconnected */ mutex_unlock(&dev->io_mutex); return -ENODEV; } @@ -440,7 +443,7 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer, goto error;
mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* already disconnected */ + if (dev->disconnected) { /* already disconnected */ mutex_unlock(&dev->io_mutex); retval = -ENODEV; goto error;