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Re: PATCH: Path MTU discovery fix

To: Daiki Ueno <ueno@xxxxxxxxxxxx>
Subject: Re: PATCH: Path MTU discovery fix
From: "David S. Miller" <davem@xxxxxxxxxx>
Date: Sat, 9 Jun 2001 23:58:28 -0700 (PDT)
Cc: netdev@xxxxxxxxxxx
In-reply-to: <m2u21o7utq.fsf@deisui.bug.org>
References: <m2u21o7utq.fsf@deisui.bug.org>
Sender: owner-netdev@xxxxxxxxxxx
Daiki Ueno writes:
 > Since 2.4.4, Path MTU discovery doesn't work for me.
 > 
 > In the function icmpv6_rcv, ICMPv6 header is extracted from skb->data,
 > rather from skb->h.raw, so the value of hdr->icmp6_mtu is not intended
 > and the call of the function rt6_pmtu_discovery makes no sense here.
 > 
 > The attached patch reverts to the same behavior of 2.4.3.

It may revert to the behavior of 2.4.3 but it is a broken
change.   pskb_may_pull() can change all of the header
pointers of the skb on you, so it has to reload skb->h.raw
or whatever to be correct.

It also must jump to discard if pskb_may_pull() fails, none of
the other code below that call is valid if it fails.

Later,
David S. Miller
davem@xxxxxxxxxx

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