linux-kernel - Re: [PATCH v2] net: sched: sch_netem: Fix a divide error in netem

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Message-ID: <20211125201729.15728683@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Thu, 25 Nov 2021 20:17:29 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
Cc:     vijayendra.suman@...cle.com, ramanan.govindarajan@...cle.com,
        george.kennedy@...cle.com, eric.dumazet@...il.com,
        syzkaller <syzkaller@...glegroups.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: sched: sch_netem: Fix a divide error in
 netem_enqueue during randomized corruption.

On Wed, 24 Nov 2021 02:47:15 -0800 Harshit Mogalapalli wrote:
> In netem_enqueue function the value of skb_headlen(skb) can be zero
> which leads to a division error during randomized corruption of the
> packet. This fix  adds a check to skb_headlen(skb) to prevent the division
> error.

Empty skbs are not sane. Is it just the fact that netlink_sendmsg()
does not pay much attention to len that's the problem? Can we fix that
instead?