From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Phong Tran <tranmanphong@gmail.com>
Cc: syzbot <syzbot+1234691fec1b8ceba8b1@syzkaller.appspotmail.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
lkml <linux-kernel@vger.kernel.org>,
"open list:HID CORE LAYER" <linux-input@vger.kernel.org>
Subject: Re: [Linux-kernel-mentees] [PATCH] HID: hid-lg4ff: Fix uninit-value set_autocenter_default
Date: Mon, 25 Nov 2019 16:14:31 +0100 [thread overview]
Message-ID: <CAO-hwJ+r+n4Dy+jqSuCk-vApfP-PR4o2oTzt4XWxH5jUQOeFwA@mail.gmail.com> (raw)
In-Reply-To: <0407e8bb-bbf5-ec64-cdac-ef266f1ab391@gmail.com>
On Tue, Nov 19, 2019 at 2:30 PM Phong Tran <tranmanphong@gmail.com> wrote:
>
> On 11/18/19 4:43 PM, Benjamin Tissoires wrote:
> > On Tue, Nov 5, 2019 at 3:18 PM Phong Tran <tranmanphong@gmail.com> wrote:
> >>
> >> syzbot found a problem using of uinit pointer in
> >> lg4ff_set_autocenter_default().
> >>
> >> Reported-by: syzbot+1234691fec1b8ceba8b1@syzkaller.appspotmail.com
> >>
> >> Tested by syzbot:
> >>
> >> https://groups.google.com/d/msg/syzkaller-bugs/ApnMLW6sfKE/Qq0bIHGEAQAJ
> >
> > This seems weird to me:
> >
> > the syzbot link above is about `hid_get_drvdata(hid)`, and, as I read
> > it, the possibility that hid might not have an initialized value.
> >
>
> In the dashboard [1] shows
> BUG: KMSAN: uninit-value in dev_get_drvdata include/linux/device.h:1388
> [inline]
> BUG: KMSAN: uninit-value in hid_get_drvdata include/linux/hid.h:628 [inline]
> BUG: KMSAN: uninit-value in lg4ff_set_autocenter_default+0x23a/0xa20
> drivers/hid/hid-lg4ff.c:477
> base on that I did the initialization the pointer in the patch.
>
> > Here you are changing the initialized values of value, entry and
> > drv_data, all 3 are never used before their first assignment.
> >
> > I have a feeling this particular syzbot check has already been fixed
> > upstream by d9d4b1e46d95 "HID: Fix assumption that devices have
> > inputs".
> >
>
> I think the commit d9d4b1 fixed this report [2] by syzbot.
>
> [1] https://syzkaller.appspot.com/bug?extid=1234691fec1b8ceba8b1
> [2] https://syzkaller.appspot.com/bug?extid=403741a091bf41d4ae79
As you can see in my long discussion with syzbot today, d9d4b1 also
fixed that one.
https://groups.google.com/forum/#!msg/syzkaller-bugs/ApnMLW6sfKE/Qq0bIHGEAQAJ
Cheers,
Benjamin
>
> regards,
> Phong.
> > Cheers,
> > Benjamin
> >
> >>
> >> Signed-off-by: Phong Tran <tranmanphong@gmail.com>
> >> ---
> >> drivers/hid/hid-lg4ff.c | 6 +++---
> >> 1 file changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c
> >> index 5e6a0cef2a06..44dfd08b0c32 100644
> >> --- a/drivers/hid/hid-lg4ff.c
> >> +++ b/drivers/hid/hid-lg4ff.c
> >> @@ -468,10 +468,10 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
> >> static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
> >> {
> >> struct hid_device *hid = input_get_drvdata(dev);
> >> - s32 *value;
> >> + s32 *value = NULL;
> >> u32 expand_a, expand_b;
> >> - struct lg4ff_device_entry *entry;
> >> - struct lg_drv_data *drv_data;
> >> + struct lg4ff_device_entry *entry = NULL;
> >> + struct lg_drv_data *drv_data = NULL;
> >> unsigned long flags;
> >>
> >> drv_data = hid_get_drvdata(hid);
> >> --
> >> 2.20.1
> >>
> >
>
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prev parent reply other threads:[~2019-11-25 15:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 14:18 [Linux-kernel-mentees] [PATCH] HID: hid-lg4ff: Fix uninit-value set_autocenter_default Phong Tran
2019-11-18 9:43 ` Benjamin Tissoires
2019-11-19 13:29 ` Phong Tran
2019-11-25 15:14 ` Benjamin Tissoires [this message]
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