[PATCH 4.4 41/46] usblp: fix race between disconnect() and read()

Greg Kroah-Hartman
2020-09-21T16:33:46Z

From: Oliver Neukum <oneukum@suse.com>

commit 9cdabcb3ef8c24ca3a456e4db7b012befb688e73 upstream.

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

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+be5b5f86a162a6c281e6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20200917103427.15740-1-oneukum@suse.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/class/usblp.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -840,6 +840,11 @@ static ssize_t usblp_read(struct file *f
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);