Re: [patch 29/37] dvb-core: Proper handling ULE SNDU length of 0

Ang Way Chuang
2006-09-20T09:38:32Z

Hi Marcel,

Marcel Holtmann wrote:
> Hi Michael,
>
>> >>>> Can we hold off on this until the 2.6.17.13 review cycle? This patch
>> >>>> has not been sent to the linux-dvb mailing list, it has not been
>> >>>> reviewed or tested except for the Author and Marcel.
>> >>> Yes, I've now moved it, thanks.
>> >> Marcel Siegert and I spoke about this today -- We are doing things a
>> >> bit differently for 2.6.18 and later, but this patch is appropriate for
>> >> 2.6.17.y
>> >
>> > so this means it is fixed in 2.6.18 or is it still vulnerable. If it is
>> > still vulnerable, then we need a fix. And we need it now.
>>
>> 2.6.18 should not be vulnerable. See the following changeset in Linus'
>> tree:
>>
>> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blobdiff;h=8859ab74f0fe4c65c8e75b9350a2a0b138615525;hp=9fd87521a1639bd3dae51dcdce48545614d41a85;hb=18232ca61b4c73b849850200a5e6ec40517f35ab;f=drivers/media/dvb/dvb-core/dvb_net.c
>>
>> Quoting MWS from irc:
>>
>> if the len is smaller than 4 or if dbit set smaller than 4+ealen, just
>> get rid of that packet and interpret as error. the 2.6.18 is not letting
>> them through if they are < sizeof(5), so 4 byte packets would be ignored.
>
> I saw the changeset in the current 2.6.18-rc kernel and this was the
> reason for me asking. I don't have the hardware to reproduce this, but
> if you say that the final 2.6.18 kernel will not be vulnerable, then I
> take your word for it.
>
> Regards
>
> Marcel
>
>
>

I've tested 2.6.18-rc7 and it seems there is no problem with the case
where dbit is not set. It should not be vulnerable.
Thanks

Regards,
Ang Way Chuang
--
May you be well and happy.