linux-kernel - Re: [PATCH] fix slab-out-of-bounds Write in betop

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Message-ID: <nycvar.YFH.7.76.2108192046290.15313@cbobk.fhfr.pm>
Date:   Thu, 19 Aug 2021 20:47:22 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     "F.A.Sulaiman" <asha.16@...ac.mrt.ac.lk>
cc:     benjamin.tissoires@...hat.com, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, paskripkin@...il.com
Subject: Re: [PATCH] fix  slab-out-of-bounds Write in betop_probe

On Tue, 17 Aug 2021, F.A.Sulaiman wrote:

> This patch resolves the bug 'KASAN: slab-out-of-bounds Write in betop_probe' reported by Syzbot.
> This checkes hid_device's input is non empty before it's been used.
> 
> Signed-off-by: F.A. SULAIMAN <asha.16@...ac.mrt.ac.lk>
> ---
>  drivers/hid/hid-betopff.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/hid/hid-betopff.c b/drivers/hid/hid-betopff.c
> index 467d789f9bc2..27b57aef9a0a 100644
> --- a/drivers/hid/hid-betopff.c
> +++ b/drivers/hid/hid-betopff.c
> @@ -121,8 +121,18 @@ static int betopff_init(struct hid_device *hid)
>  
>  static int betop_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  {
> +	struct hid_input *hidinput;
> +	struct input_dev *dev;
>  	int ret;
>  
> +	if (list_empty(&hdev->inputs)) {
> +		hid_err(hdev, "no inputs found\n");
> +		return -ENODEV;
> +	}
> +
> +	hidinput = list_first_entry(&hdev->inputs, struct hid_input, list);
> +	dev = hidinput->input;
> +

Thanks for the fix. Syzbot is right though -- what is the point of the 
above assignment? Could you please resubmit a fixed up version?

Thanks,

-- 
Jiri Kosina
SUSE Labs