Re: [Security, resend] Instant crash with rtl8169 and large packets

Eric Dumazet
2009-06-08T15:07:01Z

Michael Tokarev a écrit :
> Thank you Eric for the reply.
>
> Eric Dumazet wrote:
>> Michael Tokarev a écrit :
> []
>>> The situation is very simple: with an RTL8169 (probably
>>> onboard) GigE card which, by default, is configured to
>>> have MTU (maximal transmission unit) to be 1500 bytes,
>>> it's *trivial* to instantly crash the machine by sending
>>> it a *single* packet of size >1500 bytes (provided the
>>> network switch can handle jumbo frames).
> []
>>> http://www.corpit.ru/mjt/r8169-mtu-oops.jpg
>
>> I suppose you use a recent kernel ?
>
> http://marc.info/?t=123462473200002 -- here's my first attempt,
> at Feb this year. It was 2.6.27 or so. Right now I'm running
> 2.6.29[.4]. So I think yes, I use a recent kernel.
>
>> Could you please try following patch ?
> []
>> diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
>> index e94316b..c08b97a 100644
>> --- a/drivers/net/r8169.c
>> +++ b/drivers/net/r8169.c
>> @@ -3468,7 +3468,7 @@ static int rtl8169_rx_interrupt(struct
>> net_device *dev,
>>
>> if (status & DescOwn)
>> break;
>> - if (unlikely(status & RxRES)) {
>> + if (unlikely(status & (RxRES | RxRWT | RxRUNT | RxCRC |
>> RxFOVF))) {
>> if (netif_msg_rx_err(tp)) {
>> printk(KERN_INFO
>> "%s: Rx ERROR. status = %08x\n",
>
> Tried that one, got no printk (at least not a visible one) and exactly
> the same OOPS as before. Trivial test with
>
> ping -c1 -s3000 $my_ip_addr
>
> (learned to add -c1 because the previous time my machine crashed several
> times
> in a row till I figured out what's going on and unplugged the ethernet
> cord --
> even if ping were running from an xterm executed from the machine to
> which I
> were pinging to! :)
>
> Also got ext4fs corruption when rebooted (it's a staging area so nothing
> important
> is there but still.. "interesting").
>
> Also tried 32bit kernel (were using 64bits -- exactly the same result).
>
> I wish I had a serial cable or even a serial port on this machine....
> But I guess
> it'd not help anyway, because the machine locks hard.
>
> Thanks!
>
> /mjt

OK, 2nd try then :)

Thanks

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index e94316b..9080b08 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -3495,7 +3495,8 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
* frames. They are seen as a symptom of over-mtu
* sized frames.
*/
- if (unlikely(rtl8169_fragmented_frame(status))) {
+ if (unlikely(rtl8169_fragmented_frame(status) ||
+ (unsigned int)pkt_size > tp->rx_buf_sz)) {
dev->stats.rx_dropped++;
dev->stats.rx_length_errors++;
rtl8169_mark_to_asic(desc, tp->rx_buf_sz);