netdev - Re: [PATCH] qlcnic: dont assume NET_IP

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Date:	Tue, 21 Sep 2010 12:33:38 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	amit.salecha@...gic.com
Cc:	eric.dumazet@...il.com, netdev@...r.kernel.org,
	ameen.rahman@...gic.com, anirban.chakraborty@...gic.com
Subject: Re: [PATCH] qlcnic: dont assume NET_IP_ALIGN is 2

From: Amit Salecha <amit.salecha@...gic.com>
Date: Tue, 21 Sep 2010 03:41:42 -0500

>> So in order to improve "throughput", you were allowing for memory
>> exhaust and freeze of the _machine_ ?
>>
> This won't lead to such problem. truesize is used for accounting only.

Yes, it will.

Do you understand that we enforce both socket-level and system-wide
networking buffer usage in the stack?  And this limiting is based
upon skb->truesize and therefore only works if skb->truesize is
accurate?

It's meant to keep people from attacking a server and consuming large
percentages of system memory with networking buffer memory such that
other tasks cannot complete successfully.

And by mis-reporting the truesize you are subverting that entirely.

This qlcnic truesize bug is a huge security hole, can't you see this
now?

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