linux-kernel - Re: [PATCH] wifi: mt76: mt7996: prevent uninit return in mt7996_mac_sta_add

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Message-ID: <CAOiHx==UCeMQpywQJCLPQqipEW0tK9youRxdR5+_T1LuGp_EHA@mail.gmail.com>
Date: Sat, 22 Mar 2025 12:51:57 +0100
From: Jonas Gorski <jonas.gorski@...il.com>
To: Qasim Ijaz <qasdev00@...il.com>
Cc: nbd@....name, lorenzo@...nel.org, ryder.lee@...iatek.com, 
	shayne.chen@...iatek.com, sean.wang@...iatek.com, matthias.bgg@...il.com, 
	angelogioacchino.delregno@...labora.com, chui-hao.chiu@...iatek.com, 
	Bo.Jiao@...iatek.com, linux-wireless@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] wifi: mt76: mt7996: prevent uninit return in mt7996_mac_sta_add_links

Hi,

On Thu, Mar 20, 2025 at 9:19 PM Qasim Ijaz <qasdev00@...il.com> wrote:
>
> If link_conf_dereference_protected() or mt7996_vif_link()
> or link_sta_dereference_protected() fail the code jumps to
> the error_unlink label and returns ret which is uninitialised.
>
> Fix this by setting err before jumping to error_unlink.
>
> Fixes: c7e4fc362443 ("wifi: mt76: mt7996: Update mt7996_mcu_add_sta to MLO support")
> Fixes: dd82a9e02c05 ("wifi: mt76: mt7996: Rely on mt7996_sta_link in sta_add/sta_remove callbacks")
> Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7996/main.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/main.c b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
> index 91c64e3a0860..78f7f1fc867e 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7996/main.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
> @@ -998,16 +998,22 @@ mt7996_mac_sta_add_links(struct mt7996_dev *dev, struct ieee80211_vif *vif,
>                         continue;
>
>                 link_conf = link_conf_dereference_protected(vif, link_id);
> -               if (!link_conf)
> +               if (!link_conf) {
> +                       err = -EINVAL;
>                         goto error_unlink;
> +               }
>
>                 link = mt7996_vif_link(dev, vif, link_id);
> -               if (!link)
> +               if (!link) {
> +                       err = -EINVAL;
>                         goto error_unlink;
> +               }
>
>                 link_sta = link_sta_dereference_protected(sta, link_id);
> -               if (!link_sta)
> +               if (!link_sta) {
> +                       err = -EINVAL

You are missing a semicolon at the end of the line.

To also do some bike shedding, you could initialize err (with 0 or
-EINVAL), and then change the err return to return err ? : -EINVAL;.
But your way has an explicit error code assigned to each failure, even
if it is always the same. So I won't claim my suggestion is better.

Best regards,
Jonas