linux-kernel - Re: [PATCH v2] drivers/hid/hid-multitouch.c: fix a possible null pointer access.

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Date:   Thu, 19 Dec 2019 10:25:44 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Pan Zhang <zhangpan26@...wei.com>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Henrik Rydberg <rydberg@...math.org>, hushiyuan@...wei.com,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drivers/hid/hid-multitouch.c: fix a possible null
 pointer access.

On Thu, Dec 19, 2019 at 3:46 AM Pan Zhang <zhangpan26@...wei.com> wrote:
>
> 1002     if ((quirks & MT_QUIRK_IGNORE_DUPLICATES) && mt) {
> 1003         struct input_mt_slot *i_slot = &mt->slots[slotnum];
> 1004
> 1005         if (input_mt_is_active(i_slot) &&
> 1006             input_mt_is_used(mt, i_slot))
> 1007             return -EAGAIN;
> 1008     }
>
> We previously assumed 'mt' could be null (see line 1002).
>
> The following situation is similar, so add a judgement.
>
> Signed-off-by: Pan Zhang <zhangpan26@...wei.com>
> ---

Thanks a lot for the quick respin.

Applied to for-5.5/upstream-fixes

Cheers,
Benjamin

>  drivers/hid/hid-multitouch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 3cfeb16..368de81 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -1019,7 +1019,7 @@ static int mt_process_slot(struct mt_device *td, struct input_dev *input,
>                 tool = MT_TOOL_DIAL;
>         else if (unlikely(!confidence_state)) {
>                 tool = MT_TOOL_PALM;
> -               if (!active &&
> +               if (!active && mt &&
>                     input_mt_is_active(&mt->slots[slotnum])) {
>                         /*
>                          * The non-confidence was reported for
> --
> 2.7.4
>