On Mon, Jul 29, 2024 at 4:23 AM <andrey.konovalov@xxxxxxxxx> wrote: > > From: Andrey Konovalov <andreyknvl@xxxxxxxxx> > > Commit a7f3813e589f ("usb: gadget: dummy_hcd: Switch to hrtimer transfer > scheduler") switched dummy_hcd to use hrtimer and made the timer's > callback be executed in the hardirq context. > > With that change, __usb_hcd_giveback_urb now gets executed in the hardirq > context, which causes problems for KCOV and KMSAN. > > One problem is that KCOV now is unable to collect coverage from > the USB code that gets executed from the dummy_hcd's timer callback, > as KCOV cannot collect coverage in the hardirq context. > > Another problem is that the dummy_hcd hrtimer might get triggered in the > middle of a softirq with KCOV remote coverage collection enabled, and that > causes a WARNING in KCOV, as reported by syzbot. (I sent a separate patch > to shut down this WARNING, but that doesn't fix the other two issues.) > > Finally, KMSAN appears to ignore tracking memory copying operations > that happen in the hardirq context, which causes false positive > kernel-infoleaks, as reported by syzbot. > > Change the hrtimer in dummy_hcd to execute the callback in the softirq > context. > > Reported-by: syzbot+2388cdaeb6b10f0c13ac@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=2388cdaeb6b10f0c13ac > Reported-by: syzbot+17ca2339e34a1d863aad@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=17ca2339e34a1d863aad > Fixes: a7f3813e589f ("usb: gadget: dummy_hcd: Switch to hrtimer transfer scheduler") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Hi Greg, Could you pick up either this or Marcello's patch (https://lkml.org/lkml/2024/6/26/969)? In case they got lost. Thank you!