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Date:   Wed, 23 Jun 2021 12:56:20 +0530
From:   Anirudh Rayabharam <mail@anirudhrb.com>
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, gregkh@linuxfoundation.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        syzbot+b2645b5bf1512b81fa22@syzkaller.appspotmail.com,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, mail@anirudhrb.com
Subject: Re: [PATCH] mac80211_hwsim: correctly handle zero length frames
Message-ID: <YNLiHJuD3GuDgbKR@anirudhrb.com>
References: <20210610161916.9307-1-mail@anirudhrb.com>
 <a3589e399e179b389e90df36acb67ae1ec7dea97.camel@sipsolutions.net>
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On Fri, Jun 18, 2021 at 11:36:16AM +0200, Johannes Berg wrote:
> On Thu, 2021-06-10 at 21:49 +0530, Anirudh Rayabharam wrote:
> > syzbot, using KMSAN, has reported an uninit-value access in
> > hwsim_cloned_frame_received_nl(). This is happening because frame_data_len
> > is 0. The code doesn't detect this case and blindly tries to read the
> > frame's header.
> > 
> > Fix this by bailing out in case frame_data_len is 0.
> 
> This really seems quite pointless - you should bail out if the frame is
> too short for what we need to do, not just when it's 0.

That makes sense. Do you happen to know what the min length of a valid
frame is? There doesn't seem to be constant defined for that already.

	- Anirudh

> 
> johannes
>