From: Phong Tran <tranmanphong@gmail.com>
To: Benjamin Tissoires <benjamin.tissoires@redhat.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: Tue, 19 Nov 2019 20:29:49 +0700 [thread overview]
Message-ID: <0407e8bb-bbf5-ec64-cdac-ef266f1ab391@gmail.com> (raw)
In-Reply-To: <CAO-hwJ+cydMPQE_otc8-67=SDKmjac5RXsLs-9x6dH4YqA+DVQ@mail.gmail.com>
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
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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next prev parent reply other threads:[~2019-11-19 13:36 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 [this message]
2019-11-25 15:14 ` Benjamin Tissoires
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