appledisplay: fix error handling in the scheduled work

The work item can operate on

1. stale memory left over from the last transfer
the actual length of the data transfered needs to be checked
2. memory already freed
the error handling in appledisplay_probe() needs
to cancel the work in that case

Reported-and-tested-by: syzbot+495dab1f175edc9c2f13@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191106124902.7765-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2019-11-06 13:49:01 +01:00 committed by Greg Kroah-Hartman
parent c1f602da92
commit 91feb01596

View File

@ -164,7 +164,12 @@ static int appledisplay_bl_get_brightness(struct backlight_device *bd)
0,
pdata->msgdata, 2,
ACD_USB_TIMEOUT);
brightness = pdata->msgdata[1];
if (retval < 2) {
if (retval >= 0)
retval = -EMSGSIZE;
} else {
brightness = pdata->msgdata[1];
}
mutex_unlock(&pdata->sysfslock);
if (retval < 0)
@ -299,6 +304,7 @@ error:
if (pdata) {
if (pdata->urb) {
usb_kill_urb(pdata->urb);
cancel_delayed_work_sync(&pdata->work);
if (pdata->urbdata)
usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
pdata->urbdata, pdata->urb->transfer_dma);