Date:	Mon, 08 Jun 2009 17:59:36 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Michael Tokarev <mjt@....msk.ru>
CC:	Linux-kernel <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [Security, resend] Instant crash with rtl8169 and large packets

Michael Tokarev a écrit :
> 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).
> []
>> OK, 2nd try then :)
> 
>> 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);
> 
> This one behaves much better.  There's no instant crash anymore, and the
> 'dropped' and 'frame' stats in ifconfig gets incremented with each ping.
> 
> It fails down the line however.  I wasn't able to reply to this email after
> doing the ping test with the above change (no more large packets were
> sent).
> With OOPSes like this one:
> 
>  general protection fault: 0000 [#1] SMP
>  last sysfs file:
> /sys/devices/pci0000:00/0000:00:01.0/0000:01:05.0/drm/card0/dev
>  CPU 0
>  Modules linked in: radeon drm r8169 powernow_k8 autofs4 nfsd nfs lockd
> nfs_acl auth_rpcgss sunrpc quota_v2
>  Pid: 10917, comm: icedove-bin Not tainted 2.6.29-x86-64 #2.6.29.4
> System Product Name
>  RIP: 0010:[<ffffffff8029889b>]  [<ffffffff8029889b>] put_page+0x1b/0x170
>  RSP: 0018:ffff8800cd8fdb88  EFLAGS: 00210296
>  RAX: 0000000000000020 RBX: 6d6c6b6a69686766 RCX: 0000000000000760
>  RDX: ffff88011d9f1680 RSI: ffff88011d9f139b RDI: 6d6c6b6a69686766
>  RBP: ffff88011c936ac0 R08: 0000000000000001 R09: 0000000000000000
>  R10: ffffffff80552840 R11: 0000000000200293 R12: ffff88011d03e080
>  R13: 0000000000000030 R14: ffff88011d03e4bc R15: 0000000000000000
>  FS:  0000000000000000(0000) GS:ffffffff80608000(0063)
> knlGS:00000000f220bb90
>  CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
>  CR2: 000000000820302c CR3: 0000000116c57000 CR4: 00000000000006e0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
>  Process icedove-bin (pid: 10917, threadinfo ffff8800cd8fc000, task
> ffff8801158d8820)
>  Stack:
>   0000000000000000 0000000000000001 ffff88011c936ac0 ffff88011d03e080
>   0000000000000030 ffffffff803dbc7f 0000000000000319 ffff88011c936ac0
>   0000000000000000 ffffffff803db911 ffff88011c936ac0 ffffffff80418a88
>  Call Trace:
>   [<ffffffff803dbc7f>] ? skb_release_data+0xaf/0xe0
>   [<ffffffff803db911>] ? __kfree_skb+0x11/0xa0
>   [<ffffffff80418a88>] ? tcp_recvmsg+0x6d8/0x950
>   [<ffffffff8046f91e>] ? _spin_lock_irqsave+0x2e/0x40
>   [<ffffffff803d61b0>] ? sock_common_recvmsg+0x30/0x50
>   [<ffffffff803d4365>] ? sock_recvmsg+0xd5/0x110
>   [<ffffffff80244640>] ? default_wake_function+0x0/0x10
>   [<ffffffff802d5019>] ? file_update_time+0x59/0x140
>   [<ffffffff80261e90>] ? autoremove_wake_function+0x0/0x30
>   [<ffffffff8046fa25>] ? _spin_lock+0x5/0x10
>   [<ffffffff8026f109>] ? futex_wake+0x129/0x140
>   [<ffffffff803d3ab2>] ? sockfd_lookup_light+0x22/0x90
>   [<ffffffff803d56e9>] ? sys_recvfrom+0xe9/0x180
>   [<ffffffff80261e90>] ? autoremove_wake_function+0x0/0x30
>   [<ffffffff8046d8c5>] ? thread_return+0x3d/0x6d8
>   [<ffffffff803f6c86>] ? compat_sys_socketcall+0x136/0x1f0
>   [<ffffffff80238c47>] ? cstar_dispatch+0x7/0x4a
>  Code: 2c fd ff ff eb db 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec 28 48 89
> 5c 24 08 48 89 6c 24 10 48 89 fb 4c
>  RIP  [<ffffffff8029889b>] put_page+0x1b/0x170
>   RSP <ffff8800cd8fdb88>
>  ---[ end trace c2d84c667e0d946d ]---
> 
> (it probably has nothing to do with radeon drm sysfs file
> (it is NOT the binary fglrx module by the way)).
> 
> Looks like some memory corruption.  And most probably it is in
> that error path in r8169 driver - it is the only new codepath
> which were executed here.  The problem is quite repeatable -
> after sending a single large ping system starts behaving like
> the above at random.
> 
> So we're on a right way it seems, but there's more than one
> issue here.
> 
> By the way, is there anything else we can do here but drop the
> packet?  Or is there any REASON to do something else?
> 

Hmm... this code path is not new, I believe your adapter is buggy, because it
is overwriting part of memory it should not touch at all.

When this driver queues a skb in rx queue, it tells NIC the max size of the skb,
and apparently NIC happily delivers packets with larger sizes, so probably DMA
wrote data past end of skb data.

Try to change 

static void rtl_set_rx_max_size(void __iomem *ioaddr)
    RTL_W16(RxMaxSize, 16383); 

to ->

    RTL_W16(RxMaxSize, RX_BUF_SIZE);


(But it will probably break jumbo frames rx as well)


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