Subject: Re: [PATCH] rt2x00: reset reg earlier in rt2500usb_register_read

From: Greg KH <[email-masked]>
Date: Thu, 21 Jan 2021 12:20:21 +0100

On Thu, Jan 21, 2021 at 06:59:08PM +0800, 慕冬亮 wrote:
> On Thu, Jan 21, 2021 at 5:49 PM Greg KH <[email-masked]> wrote:
> >
> > On Thu, Jan 21, 2021 at 05:20:26PM +0800, Dongliang Mu wrote:
> > > In the function rt2500usb_register_read(_lock), reg is uninitialized
> > > in some situation. Then KMSAN reports uninit-value at its first memory
> > > access. To fix this issue, add one reg initialization in the function
> > > rt2500usb_register_read and rt2500usb_register_read_lock
> > >
> > > BUG: KMSAN: uninit-value in rt2500usb_init_eeprom rt2500usb.c:1443 [inline]
> > > BUG: KMSAN: uninit-value in rt2500usb_probe_hw+0xb5e/0x22a0 rt2500usb.c:1757
> > > CPU: 0 PID: 3369 Comm: kworker/0:2 Not tainted 5.3.0-rc7+ #0
> > > Hardware name: Google Compute Engine
> > > Workqueue: usb_hub_wq hub_event
> > > Call Trace:
> > >  __dump_stack lib/dump_stack.c:77 [inline]
> > >  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
> > >  kmsan_report+0x162/0x2d0 mm/kmsan/kmsan_report.c:109
> > >  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:294
> > >  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1443 [inline]
> > >  rt2500usb_probe_hw+0xb5e/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
> > >  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
> > >  rt2x00usb_probe+0x7ae/0xf60 wireless/ralink/rt2x00/rt2x00usb.c:842
> > >  rt2500usb_probe+0x50/0x60 wireless/ralink/rt2x00/rt2500usb.c:1966
> > >  ......
> > >
> > > Local variable description: ----reg.i.i@rt2500usb_probe_hw
> > > Variable was created at:
> > >  rt2500usb_register_read wireless/ralink/rt2x00/rt2500usb.c:51 [inline]
> > >  rt2500usb_init_eeprom wireless/ralink/rt2x00/rt2500usb.c:1440 [inline]
> > >  rt2500usb_probe_hw+0x774/0x22a0 wireless/ralink/rt2x00/rt2500usb.c:1757
> > >  rt2x00lib_probe_dev+0xba9/0x3260 wireless/ralink/rt2x00/rt2x00dev.c:1427
> > >
> > > Signed-off-by: Dongliang Mu <[email-masked]>
> > > ---
> > >  drivers/net/wireless/ralink/rt2x00/rt2500usb.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > index fce05fc88aaf..f6c93a25b18c 100644
> > > --- a/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > +++ b/drivers/net/wireless/ralink/rt2x00/rt2500usb.c
> > > @@ -48,6 +48,7 @@ static u16 rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
> > >                                  const unsigned int offset)
> > >  {
> > >       __le16 reg;
> > > +     memset(&reg, 0, sizeof(reg));
> >
> > As was pointed out, just set reg = 0 on the line above please.
> 
> I've sent another patch.
> 
> BTW, I set "--subject-prefix="PATCH v2" in my git-send-mail command.
> But it does not show "v2" in the subject of the new email.

You can set the "v2" in the 'git format-patch' option, right?

thanks,

greg k-h