3.16.80-rc1 review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan@kernel.org
commit eb7f5a490c5edfe8126f64bc58b9ba2edef0a425 upstream.
Make sure to stop all I/O on disconnect by adding a disconnected flag which is used to prevent new I/O from being started and by stopping all ongoing I/O before returning.
This also fixes a potential use-after-free on driver unbind in case the driver data is freed before the completion handler has run.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20190926091228.24634-7-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/misc/usblcd.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-)
--- a/drivers/usb/misc/usblcd.c +++ b/drivers/usb/misc/usblcd.c @@ -17,6 +17,7 @@ #include <linux/slab.h> #include <linux/errno.h> #include <linux/mutex.h> +#include <linux/rwsem.h> #include <linux/uaccess.h> #include <linux/usb.h>
@@ -56,6 +57,8 @@ struct usb_lcd { using up all RAM */ struct usb_anchor submitted; /* URBs to wait for before suspend */ + struct rw_semaphore io_rwsem; + unsigned long disconnected:1; }; #define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)
@@ -141,6 +144,13 @@ static ssize_t lcd_read(struct file *fil
dev = file->private_data;
+ down_read(&dev->io_rwsem); + + if (dev->disconnected) { + retval = -ENODEV; + goto out_up_io; + } + /* do a blocking bulk read to get data from the device */ retval = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, @@ -157,6 +167,9 @@ static ssize_t lcd_read(struct file *fil retval = bytes_read; }
+out_up_io: + up_read(&dev->io_rwsem); + return retval; }
@@ -236,11 +249,18 @@ static ssize_t lcd_write(struct file *fi if (r < 0) return -EINTR;
+ down_read(&dev->io_rwsem); + + if (dev->disconnected) { + retval = -ENODEV; + goto err_up_io; + } + /* create a urb, and a buffer for it, and copy the data to the urb */ urb = usb_alloc_urb(0, GFP_KERNEL); if (!urb) { retval = -ENOMEM; - goto err_no_buf; + goto err_up_io; }
buf = usb_alloc_coherent(dev->udev, count, GFP_KERNEL, @@ -277,6 +297,7 @@ static ssize_t lcd_write(struct file *fi the USB core will eventually free it entirely */ usb_free_urb(urb);
+ up_read(&dev->io_rwsem); exit: return count; error_unanchor: @@ -284,7 +305,8 @@ error_unanchor: error: usb_free_coherent(dev->udev, count, buf, urb->transfer_dma); usb_free_urb(urb); -err_no_buf: +err_up_io: + up_read(&dev->io_rwsem); up(&dev->limit_sem); return retval; } @@ -327,6 +349,7 @@ static int lcd_probe(struct usb_interfac } kref_init(&dev->kref); sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES); + init_rwsem(&dev->io_rwsem); init_usb_anchor(&dev->submitted);
dev->udev = usb_get_dev(interface_to_usbdev(interface)); @@ -437,6 +460,12 @@ static void lcd_disconnect(struct usb_in /* give back our minor */ usb_deregister_dev(interface, &lcd_class);
+ down_write(&dev->io_rwsem); + dev->disconnected = 1; + up_write(&dev->io_rwsem); + + usb_kill_anchored_urbs(&dev->submitted); + /* decrement our usage count */ kref_put(&dev->kref, lcd_delete);