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From: "Toke Høiland-Jørgensen" <>
To: Stephen Hemminger <>
Cc: David Miller <>,,
Subject: Re: [PATCH net 2/2] sch_cake: Make sure we can write the IP header before changing DSCP bits
Date: Thu, 04 Apr 2019 22:44:33 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20190404123536.3c966937@shemminger-XPS-13-9360>

Stephen Hemminger <> writes:

> On Thu, 04 Apr 2019 15:01:33 +0200
> Toke Høiland-Jørgensen <> wrote:
>>  static u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)
>>  {
>> +	int wlen = skb_network_offset(skb);
> In theory this could be negative, you should handle that?
> Rather than calling may_pull() with a huge unsigned value.

Huh, that would imply that skb->network_header points to before
skb->head; when does that happen?

Also, pskb_may_pull() does check for len > skb->len, so I guess a
follow-up question would be, "does it happen often enough to warrant
handling at this level"?

Also, I copied that bit from sch_dsmark, so if you really thing it needs
to be fixed, I guess we should fix both...


  reply	other threads:[~2019-04-04 20:44 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-04 13:01 [PATCH net 0/2] sched: A few small fixes for sch_cake Toke Høiland-Jørgensen
2019-04-04 13:01 ` [PATCH net 1/2] sch_cake: Use tc_skb_protocol() helper for getting packet protocol Toke Høiland-Jørgensen
2019-04-04 13:01 ` [PATCH net 2/2] sch_cake: Make sure we can write the IP header before changing DSCP bits Toke Høiland-Jørgensen
2019-04-04 19:35   ` Stephen Hemminger
2019-04-04 20:44     ` Toke Høiland-Jørgensen [this message]
2019-04-04 21:40       ` Stephen Hemminger
2019-04-04 21:55         ` Toke Høiland-Jørgensen
2019-04-04 17:56 ` [PATCH net 0/2] sched: A few small fixes for sch_cake David Miller

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