From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Phong Tran <tranmanphong@gmail.com>
Cc: 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, 18 Nov 2019 10:43:21 +0100 [thread overview]
Message-ID: <CAO-hwJ+cydMPQE_otc8-67=SDKmjac5RXsLs-9x6dH4YqA+DVQ@mail.gmail.com> (raw)
In-Reply-To: <20191105141807.27054-1-tranmanphong@gmail.com>
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.
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".
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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next prev parent reply other threads:[~2019-11-18 9:43 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 [this message]
2019-11-19 13:29 ` Phong Tran
2019-11-25 15:14 ` Benjamin Tissoires
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