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

Michael Tokarev a écrit :

Thank you Eric for the reply.

Eric Dumazet wrote:

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Michael Tokarev a écrit :

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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).

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 http://www.corpit.ru/mjt/r8169-mtu-oops.jpg

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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.

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Could you please try following patch ?

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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);