linux-kernel - Re: [PATCH] drivers: input: input: Fix possible sleep-in-atomic bug in input_alloc

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Message-ID: <ZFkOuOmkIiYuQBpz@google.com>
Date:   Mon, 8 May 2023 08:01:12 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Teng Qi <starmiku1207184332@...il.com>
Cc:     rydberg@...math.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: input: input: Fix possible sleep-in-atomic bug
 in input_alloc_absinfo()

On Mon, May 08, 2023 at 03:13:19PM +0800, Teng Qi wrote:
> Thank you for an alternative solution. I will take a closer look at the
> patch
> you CCed me on.
> However, I am still confused about why this cannot happen in practice.
> Could you provide more information?

The only call to input_abs_set_val() in the event processing code that
is running in an atomic context (under spinlock) is done for
ABS_MT_SLOT, and the call is protected by checks ensuring that
multitouch was set up properly for the device. This includes allocating
absinfo. Therefore while the code may trip up static analyzers the
problem will not happen in practice with the current code.

Thanks.

-- 
Dmitry