linux-kernel - Re: [PATCH] HID: wacom: handle kzalloc() allocation failure in wacom_wac_queue

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Message-ID: <247781nr-qp6o-94q0-nq26-1sq70287r9r9@xreary.bet>
Date: Thu, 24 Apr 2025 11:53:43 +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] HID: wacom: handle kzalloc() allocation failure in
 wacom_wac_queue_flush()

On Sat, 29 Mar 2025, Qasim Ijaz wrote:

> During wacom_wac_queue_flush() the code calls 
> kzalloc() to allocate a zero initialised buffer 
> which it uses as a storage buffer to get data 
> from the fifo via kfifo_out(). However it does not
> check kzalloc() for allocation failure which returns 
> NULL and could potentially lead to a NULL deref.
>  
> Fix this by checking for kzalloc() failure and skipping
> the current entry if allocation failure occurs.
> 
> Fixes: 5e013ad20689 ("HID: wacom: Remove static WACOM_PKGLEN_MAX limit")
> Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
> ---
>  drivers/hid/wacom_sys.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
> index 97393a3083ca..666b7eb0fdfe 100644
> --- a/drivers/hid/wacom_sys.c
> +++ b/drivers/hid/wacom_sys.c
> @@ -70,10 +70,16 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
>  {
>  	while (!kfifo_is_empty(fifo)) {
>  		int size = kfifo_peek_len(fifo);
> -		u8 *buf = kzalloc(size, GFP_KERNEL);
> +		u8 *buf;
>  		unsigned int count;
>  		int err;
>  
> +		buf = kzalloc(size, GFP_KERNEL);
> +		if (!buf) {
> +			kfifo_skip(fifo);
> +			continue;
> +		}
> +
>  		count = kfifo_out(fifo, buf, size);
>  		if (count != size) {
>  			// Hard to say what is the "right" action in this

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs