usblp: fix race between disconnect() and read()

read() needs to check whether the device has been
disconnected before it tries to talk to the device.

Signed-off-by: Oliver Neukum <[email protected]>
Reported-by: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 084c48c5848fc90354216254ffbd48c17a7be030..67cbd42421bee7e5776659a5f7ebfb077564a457 100644 (file)
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -827,6 +827,11 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t len, lo
        if (rv < 0)
                return rv;
 
+       if (!usblp->present) {
+               count = -ENODEV;
+               goto done;
+       }
+
        if ((avail = usblp->rstatus) < 0) {
                printk(KERN_ERR "usblp%d: error %d reading from printer\n",
                    usblp->minor, (int)avail);