Re: [Qemu-devel] e1000 memory corruption in guest OS

[Don Slutz <dslutz@verizon.com>]

On 03/03/14 05:47, Alexey Kardashevskiy wrote:
> On 03/03/2014 07:33 PM, Paolo Bonzini wrote:
>> Il 03/03/2014 02:58, Alexey Kardashevskiy ha scritto:
>>> On 03/02/2014 08:31 AM, Paolo Bonzini wrote:
>>>> Il 01/03/2014 13:30, Alexey Kardashevskiy ha scritto:
>>>>>>> Corrupted DMA buffer is 0x e00000 -- 0x7f15c313f000.
>>>>>>> The e1000 packet is at  0x12ffac2 -- 0x7f15c313eac2.
>>>>>>>
>>>>>>> (0x7f15c313f000 - 0x7f15c313eac2) = 0x53e which is less than 0x5aa and
>>>>>>> (0x5aa - 0x53e) = 0x6c bytes get corrupted.
>>>>>>>
>>>>>>> I see here buffer overrun from e1000 and I suspect that your patch just
>>>>>>> hides this problem. What did I miss?
>>>>> Ping, anyone?
>>>> You missed that this is a Xen-specific problem.  Xen maps things a page at
>>>> a time, so address_space_map/unmap/rw can operate only on a small part of
>>>> the requested [address, address+length) range.
>>> Sorry, I am not following you here. Does KVM map things not page-aligned?
>> Look in exec.c for xen_enabled().  Xen's implementation of
>> address_space_map/unmap is completely different.
> Honestly cannot see much difference in the current QEMU...
>
>>>> So there is no overrun in e1000.  The patch is incomplete, because it fixes
>>>> only address_space_rw, but the problem is indeed in exec.c.
>>> So you know what the problem is? We have a bunch of bugreports against
>>> e1000 breaking things...
>> This one had been reported and fixed already.
> Any hint? :) Could not spot any related to overrun except:
> a0ae17a 8 months ago Andrew Jones e1000: cleanup process_tx_desc
> but commit message says "complaints are false positives"...
>
>

Looks like you have also ignored:

http://marc.info/?l=qemu-devel&m=139325054822857&w=2
http://marc.info/?l=qemu-devel&m=139325135123159&w=2


     -Don Slutz