On Wed, Nov 6, 2019 at 1:10 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > On Wed, Nov 6, 2019 at 12:37 AM Phong Tran <tranmanphong@xxxxxxxxx> wrote: > > > > In context of USB disconnect, the delaywork trigger and calling > > appledisplay_bl_get_brightness() and the msgdata was freed. > > > > add the checking return value of usb_control_msg() and only update the > > data while the retval is valid. > > > > Reported-by: syzbot+495dab1f175edc9c2f13@xxxxxxxxxxxxxxxxxxxxxxxxx > > Reported-and-tested-by: > > syzbot+495dab1f175edc9c2f13@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > https://groups.google.com/d/msg/syzkaller-bugs/dRmkh2UYusY/l2a6Mg3FAQAJ > > Hi Phong, > > FYI, when testing patches with the usb-fuzzer instance, you need to > provide the same kernel commit id as the one where the bug was > triggered. Please see here for details: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#usb-bugs > > > > > Signed-off-by: Phong Tran <tranmanphong@xxxxxxxxx> > > --- > > drivers/usb/misc/appledisplay.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c > > index ac92725458b5..3e3dfa5a3954 100644 > > --- a/drivers/usb/misc/appledisplay.c > > +++ b/drivers/usb/misc/appledisplay.c > > @@ -164,7 +164,8 @@ static int appledisplay_bl_get_brightness(struct backlight_device *bd) > > 0, > > pdata->msgdata, 2, > > ACD_USB_TIMEOUT); > > - brightness = pdata->msgdata[1]; > > + if (retval >= 0) > > + brightness = pdata->msgdata[1]; > > mutex_unlock(&pdata->sysfslock); > > > > if (retval < 0) > > -- > > 2.20.1 > >
