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    SubjectRe: [PATCH 2.6.14-rc2] aoe [1/2]: explicitly set minimum packet length to ETH_ZLEN
    On Mon, 26 Sep 2005 Valdis.Kletnieks@vt.edu wrote:
    > On Mon, 26 Sep 2005 12:50:28 EDT, Ed L Cashin said:
    > > "Ed L. Cashin" <ecashin@coraid.com> writes:
    > >
    > > ...
    > > > Explicitly set the minimum packet length to ETH_ZLEN.
    > > >
    > > > Index: 2.6.14-rc2-aoe/drivers/block/aoe/aoecmd.c
    > > > ===================================================================
    > > > --- 2.6.14-rc2-aoe.orig/drivers/block/aoe/aoecmd.c 2005-09-26 12:20:34.000000000 -0400
    > > > +++ 2.6.14-rc2-aoe/drivers/block/aoe/aoecmd.c 2005-09-26 12:27:49.000000000 -0400
    > > > @@ -20,6 +20,9 @@
    > > > {
    > > > struct sk_buff *skb;
    > > >
    > > > + if (len < ETH_ZLEN)
    > > > + len = ETH_ZLEN;
    > > > +
    > > > skb = alloc_skb(len, GFP_ATOMIC);
    > >
    > > This change fixes some strange problems observed on a system that was
    > > using the e1000 network driver. Is the network driver supposed to
    > > ensure that ethernet packets are up to spec, at least 60 bytes long?
    >
    > I haven't chased through the code in detail - will this change ensure that
    > all ETH_ZLEN bytes are initialized? We had a bunch of drivers a few years
    > ago that set the length to the legal min, but then only copied some smaller
    > number of bytes in, resulting in leakage of kernel memory contents....

    Good point.

    On Ed's other question (which I have already trashed -- sorry),
    I am familiar with some NICs that automatically pad packets to
    ensure min packet size packets, and they know to do so with
    a safe data pattern. However, it's been a few years since I
    worked on NIC drivers, so I don't know the current state of
    affairs.

    --
    ~Randy
    -
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