Fri, Jan 31, 2014 at 08:02:07PM +0400, Andrey Borzenkov wrote:
> В Fri, 31 Jan 2014 13:35:11 -0200
> Paulo Flabiano Smorigo <pfsmor...@linux.vnet.ibm.com> пишет:
>
> > * grub-core/net/arp.c (grub_net_arp_receive): Trim arp packets with
> > abnormal size.
> >
> > GRUB uses arp request to create the arp response. If the incoming packet is
> > foobared, GRUB needs to trim the arp response packet before sending it.
> >
> > This is just a fix in time for 2.02. I'm planning to rewrite the arp
> > response code
> > after the release.
> >
> > diff --git a/ChangeLog b/ChangeLog
> > index cfa9c83..10e9c3d 100644
> > --- a/ChangeLog
> > +++ b/ChangeLog
> > @@ -1,3 +1,11 @@
> > +2014-01-31 Paulo Flabiano Smorigo <pfsmor...@br.ibm.com>
> > +
> > + * grub-core/net/arp.c (grub_net_arp_receive): Trim arp packets with
> > + abnormal size.
> > +
> > + GRUB uses arp request to create the arp response. If the incoming
> > packet is
> > + foobared, GRUB needs to trim the arp response packet before sending it.
> > +
> > 2014-01-29 Vladimir Serbinenko <phco...@gmail.com>
> >
> > * grub-core/disk/ahci.c: Increase timeout. Some SSDs take up to
> > diff --git a/grub-core/net/arp.c b/grub-core/net/arp.c
> > index d62d0cc..77581f4 100644
> > --- a/grub-core/net/arp.c
> > +++ b/grub-core/net/arp.c
> > @@ -162,6 +162,12 @@ grub_net_arp_receive (struct grub_net_buff *nb,
> > if (grub_net_addr_cmp (&inf->address, &target_addr) == 0
> > && grub_be_to_cpu16 (arp_header->op) == ARP_REQUEST)
> > {
> > + if ((nb->tail - nb->data) > 50)
>
> Using large ping size is quite common during network troubleshooting.
> This looks like rather arbitrary restriction. I'd say - if we were able
> to receive packet we should be able to also send packet of the same
> size; what problem does it fix?
I hit a firmware bug where after a while every packet comes with MTU
size (~1500 bytes). GRUB handles those foobared packets well and the
only problem is the case that I described above:
ARP responses are built using ARP request as its base. ARP responses
with trash are usually ignored by the network and my patch only trim the arp
responses to the corrent size, nothing more.
>
> > + {
> > + grub_dprintf ("net", "arp packet with abnormal size (%ld
> > bytes).\n",
> > + nb->tail - nb->data);
> > + nb->tail = nb->data + 50;
> > + }
> > grub_net_link_level_address_t target;
> > /* We've already checked that pln is either 4 or 16. */
> > char tmp[16];
> >
>
>
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--
Paulo Flabiano Smorigo
IBM Linux Technology Center
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