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

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