linux-kernel - Re: [PATCH 0/3] HID: hid-bigbenff: fixing three crash bugs in a gamepad driver

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Date:   Tue, 18 Feb 2020 11:40:09 +0100
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Hanno Zulla <abos@...no.de>
Cc:     Jiri Kosina <jikos@...nel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] HID: hid-bigbenff: fixing three crash bugs in a
 gamepad driver

Hi Hanno,

On Mon, Feb 17, 2020 at 4:24 PM Hanno Zulla <abos@...no.de> wrote:
>
> Hi there,
>
> the hid-bigbenff.c had three bugs causing possible kernel crashes.
>
> The first patch fixes a double free during device removal, which was
> caused by a wrong use of input_ff_create_memless(). The
> "driver-specific data to be passed into play_effect" parameter of
> input_ff_create_memless() would later be freed automatically when the ff
> device is removed. Since the driver also uses the managed resource API,
> it would automatically free the memory of this parameter twice, causing
> a general protection fault moments later.
>
> The second patch fixes the error path after hid_hw_start(), as a call
> to hid_hw_stop() is required in case of an error.
>
> The second patch also removes the hid_hw_close() call during device
> removal, as several other hid device drivers don't call this routine,
> either.
>
> The third patch adds a flag to avoid a race condition when there is
> still scheduled work left (or newly being scheduled) during or after
> device removal, which could cause a kernel crash.
>
> Thanks in advance for your review & kind regards,
>

I think the patches are correct (have you tested them with actual HW?).
However, checkpatch complains that the From and Signed-off-by email
differ. Can you send a v2 with a fix for that?

Cheers,
Benjamin