netdev - Re: [PATCH v2] cw1200: fix incorrect check to determine if no element is found in list

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Message-ID: <164924475461.19026.8095141212129340061.kvalo@kernel.org>
Date:   Wed,  6 Apr 2022 11:32:38 +0000 (UTC)
From:   Kalle Valo <kvalo@...nel.org>
To:     Xiaomeng Tong <xiam0nd.tong@...il.com>
Cc:     pizza@...ftnet.org, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, linville@...driver.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, jakobkoschel@...il.com,
        Xiaomeng Tong <xiam0nd.tong@...il.com>
Subject: Re: [PATCH v2] cw1200: fix incorrect check to determine if no element
 is
 found in list

Xiaomeng Tong <xiam0nd.tong@...il.com> wrote:

> The bug is here: "} else if (item) {".
> 
> The list iterator value will *always* be set and non-NULL by
> list_for_each_entry(), so it is incorrect to assume that the iterator
> value will be NULL if the list is empty or no element is found in list.
> 
> Use a new value 'iter' as the list iterator, while use the old value
> 'item' as a dedicated pointer to point to the found element, which
> 1. can fix this bug, due to now 'item' is NULL only if it's not found.
> 2. do not need to change all the uses of 'item' after the loop.
> 3. can also limit the scope of the list iterator 'iter' *only inside*
>    the traversal loop by simply declaring 'iter' inside the loop in the
>    future, as usage of the iterator outside of the list_for_each_entry
>    is considered harmful. https://lkml.org/lkml/2022/2/17/1032
> 
> Fixes: a910e4a94f692 ("cw1200: add driver for the ST-E CW1100 & CW1200 WLAN chipsets")
> Signed-off-by: Xiaomeng Tong <xiam0nd.tong@...il.com>

Can someone review this, please?

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20220320035436.11293-1-xiam0nd.tong@gmail.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches