Received-SPF: pass (google.com: domain of linux-wireless+bounces-762-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Message-ID: <bdabfb74-ea4f-4455-bb4c-1d93977393ea@quicinc.com>
Date: Wed, 13 Dec 2023 11:36:08 -0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 6/6] wifi: ath10k: remove duplicate memset() in 10.4 TDLS
 peer update
Content-Language: en-US
To: Kees Cook <keescook@chromium.org>
CC: Kalle Valo <kvalo@kernel.org>,
        "Gustavo A. R. Silva"
	<gustavo@embeddedor.com>,
        <ath10k@lists.infradead.org>, <linux-wireless@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20231213-wmi_host_mem_chunks_flexarray-v1-0-92922d92fa2c@quicinc.com>
 <20231213-wmi_host_mem_chunks_flexarray-v1-6-92922d92fa2c@quicinc.com>
 <202312131113.4C01D1DD5A@keescook>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <202312131113.4C01D1DD5A@keescook>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit

On 12/13/2023 11:16 AM, Kees Cook wrote:
> On Wed, Dec 13, 2023 at 09:06:44AM -0800, Jeff Johnson wrote:
>> In [1] it was identified that in ath10k_wmi_10_4_gen_tdls_peer_update()
>> the memset(skb->data, 0, sizeof(*cmd)) is unnecessary since function
>> ath10k_wmi_alloc_skb() already zeroes skb->data, so remove it.
> 
> Is .gen_tdls_peer_update only ever called after a fresh allocation? It
> wasn't obvious to me as I tried to follow the call paths. Is there harm
> in leaving this?

The only harm is a slight increase in code size and cpu cycles.

However note the skb allocation is done within
ath10k_wmi_10_4_gen_tdls_peer_update() itself, just before the code
being removed:
	skb = ath10k_wmi_alloc_skb(ar, len);
	if (!skb)
		return ERR_PTR(-ENOMEM);

And in ath10k_wmi_alloc_skb() we have:
	memset(skb->data, 0, round_len);

So the memset() being removed is always redundant.

/jeff