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USB: usblcd: fix I/O after disconnect 

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: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>	# 7bbe990c98
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>
This commit is contained in:
Johan Hovold 2019-09-26 11:12:25 +02:00 committed by Greg Kroah-Hartman
parent 976392650a
commit eb7f5a490c
1 changed files with 31 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/usb/misc/usblcd.c
View File

@ -18,6 +18,7 @@
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
@ -57,6 +58,8 @@ 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)
@ -142,6 +145,13 @@ static ssize_t lcd_read(struct file *file, char __user * buffer,
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,
@ -158,6 +168,9 @@ static ssize_t lcd_read(struct file *file, char __user * buffer,
retval = bytes_read;
}
out_up_io:
up_read(&dev->io_rwsem);
return retval;
}
@ -237,11 +250,18 @@ static ssize_t lcd_write(struct file *file, const char __user * user_buffer,
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,
@ -278,6 +298,7 @@ static ssize_t lcd_write(struct file *file, const char __user * user_buffer,
the USB core will eventually free it entirely */
usb_free_urb(urb);
up_read(&dev->io_rwsem);
exit:
return count;
error_unanchor:
@ -285,7 +306,8 @@ 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;
}
@ -325,6 +347,7 @@ static int lcd_probe(struct usb_interface *interface,
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));
@ -422,6 +445,12 @@ static void lcd_disconnect(struct usb_interface *interface)
/* 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);