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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
To:     Shayne Chen <shayne.chen@mediatek.com>,
        linux-wireless <linux-wireless@vger.kernel.org>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        Felix Fietkau <nbd@nbd.name>,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        Ryder Lee <ryder.lee@mediatek.com>,
        linux-mediatek <linux-mediatek@lists.infradead.org>,
        Shayne Chen <shayne.chen@mediatek.com>,
        Sujuan Chen <sujuan.chen@mediatek.com>
Subject: Re: [PATCH] mac80211: fix incorrect strlen of .write in debugfs
In-Reply-To: <20210108105643.10834-1-shayne.chen@mediatek.com>
References: <20210108105643.10834-1-shayne.chen@mediatek.com>
Date:   Fri, 08 Jan 2021 13:27:30 +0100
Message-ID: <8735zbipfx.fsf@toke.dk>
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Shayne Chen <shayne.chen@mediatek.com> writes:

> This fixes strlen mismatch problems happening in some .write callbacks
> of debugfs.
>
> When trying to configure airtime_flags in debugfs, an error appeared:
> # echo 0 > /sys/kernel/debug/ieee80211/phy0/airtime_flags
> ash: write error: Invalid argument
>
> The error is returned from kstrtou16() since a wrong length makes it
> miss the real end of input string.  To fix this, use count as the string
> length, and set proper end of string for a char buffer.
>
> The debug print is shown - airtime_flags_write: count =3D 2, len =3D 8,
> where the actual length is 2, but "len =3D strlen(buf)" gets 8.
>
> Also cleanup the other similar cases for the sake of consistency.
>
> Signed-off-by: Sujuan Chen <sujuan.chen@mediatek.com>
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>

Acked-by: Toke H=C3=B8iland-J=C3=B8rgensen <toke@toke.dk>