linux-kernel - Re: [PATCH RESEND] HID: wacom: fix memory leak on size mismatch in wacom_wac_queue

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Message-ID: <4n6pq9np-r49s-84o9-89q3-1021ssq14qsn@xreary.bet>
Date: Thu, 24 Apr 2025 11:54:42 +0200 (CEST)
From: Jiri Kosina <jikos@...nel.org>
To: Qasim Ijaz <qasdev00@...il.com>
cc: ping.cheng@...om.com, jason.gerecke@...om.com, bentiss@...nel.org, 
    linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] HID: wacom: fix memory leak on size mismatch in
 wacom_wac_queue_flush()

On Mon, 14 Apr 2025, Qasim Ijaz wrote:

> In wacom_wac_queue_flush() the code allocates zero initialised
> buffer which it uses as a storage buffer for copying data from
> a fifo via kfifo_out(). The kfifo_out() function returns the
> number of elements it has copied. The code checks if the number
> of copied elements does not equal the size of the fifo record,
> if it does not it simply skips the entry and continues to the
> next iteration. However it does not release the storage buffer
> leading to a memory leak.
> 
> Fix the memory leak by freeing the buffer on size mismatch.
> 
> Fixes: 5e013ad20689 ("HID: wacom: Remove static WACOM_PKGLEN_MAX limit")
> Reviewed-by: Jason Gerecke <jason.gerecke@...om.com>
> Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
> ---
>  drivers/hid/wacom_sys.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
> index 666b7eb0fdfe..3e4f823f8ee8 100644
> --- a/drivers/hid/wacom_sys.c
> +++ b/drivers/hid/wacom_sys.c
> @@ -87,6 +87,7 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
>  			// to flush seems reasonable enough, however.
>  			hid_warn(hdev, "%s: removed fifo entry with unexpected size\n",
>  				 __func__);
> +			kfree(buf);
>  			continue;
>  		}
>  		err = hid_report_raw_event(hdev, HID_INPUT_REPORT, buf, size, false);

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs