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]>
mrcsosa · Sep 17, 2020 · 9cdabcb · 9cdabcb
1 parent 2923182
commit 9cdabcb
Showing 1 changed file with 5 additions and 0 deletions.
diff --git 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);