From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Ilya Maximets <i.maximets@samsung.com>
Cc: dev@dpdk.org, Huawei Xie <huawei.xie@intel.com>,
Dyasly Sergey <s.dyasly@samsung.com>,
Heetae Ahn <heetae82.ahn@samsung.com>,
Jianfeng Tan <jianfeng.tan@intel.com>
Subject: Re: [dpdk-dev] [PATCH] vhost: fix segfault on bad descriptor address.
Date: Mon, 30 May 2016 22:25:40 +0800 [thread overview]
Message-ID: <20160530142540.GH5641@yliu-dev.sh.intel.com> (raw)
In-Reply-To: <574C1E63.3070000@samsung.com>
Hi Ilya,
Generically speaking, this patch looks good to me. But I guess still
need more time to check this issue later; I still failed to reproduce
it on my side after all. So, please allow a late merge.
Thanks.
--yliu
On Mon, May 30, 2016 at 02:05:07PM +0300, Ilya Maximets wrote:
> Ping.
>
> Best regards, Ilya Maximets.
>
> On 23.05.2016 14:04, Ilya Maximets wrote:
> > On 23.05.2016 13:57, Yuanhan Liu wrote:
> >> On Fri, May 20, 2016 at 03:50:04PM +0300, Ilya Maximets wrote:
> >>> In current implementation guest application can reinitialize vrings
> >>> by executing start after stop. In the same time host application
> >>> can still poll virtqueue while device stopped in guest and it will
> >>> crash with segmentation fault while vring reinitialization because
> >>> of dereferencing of bad descriptor addresses.
> >>>
> >>> OVS crash for example:
> >>> <------------------------------------------------------------------------>
> >>> [test-pmd inside guest VM]
> >>>
> >>> testpmd> port stop all
> >>> Stopping ports...
> >>> Checking link statuses...
> >>> Port 0 Link Up - speed 10000 Mbps - full-duplex
> >>> Done
> >>> testpmd> port config all rxq 2
> >>> testpmd> port config all txq 2
> >>> testpmd> port start all
> >>> Configuring Port 0 (socket 0)
> >>> Port 0: 52:54:00:CB:44:C8
> >>> Checking link statuses...
> >>> Port 0 Link Up - speed 10000 Mbps - full-duplex
> >>> Done
> >>
> >> I actually didn't manage to reproduce it on my side, with the
> >> vhost-example instead of OVS though. Is that all the commands
> >> to reproduce it, and run them just after start test-pmd?
> >
> > Actually, I think, packet flow should be enabled while performing
> > above actions and some traffic already should be sent through port
> > to change last used idx on vhost side.
> >
> > Something like:
> > start
> > ..wait a while.. see that packets are flowing.
> > stop
> > port stop
> > port config
> > port config
> > port start
> >>
> >>> [OVS on host]
> >>> Program received signal SIGSEGV, Segmentation fault.
> >>> rte_memcpy (n=2056, src=0xc, dst=0x7ff4d5247000) at rte_memcpy.h
> >>>
> >>> (gdb) bt
> >>> #0 rte_memcpy (n=2056, src=0xc, dst=0x7ff4d5247000)
> >>> #1 copy_desc_to_mbuf
> >>> #2 rte_vhost_dequeue_burst
> >>> #3 netdev_dpdk_vhost_rxq_recv
> >>> ...
> >>>
> >>> (gdb) bt full
> >>> #0 rte_memcpy
> >>> ...
> >>> #1 copy_desc_to_mbuf
> >>> desc_addr = 0
> >>> mbuf_offset = 0
> >>> desc_offset = 12
> >>> ...
> >>> <------------------------------------------------------------------------>
> >>>
> >>> Fix that by checking addresses of descriptors before using them.
> >>>
> >>> Note: For mergeable buffers this patch checks only guest's address for
> >>> zero, but in non-meargeable case host's address checked. This is done
> >>> because checking of host's address in mergeable case requires additional
> >>> refactoring to keep virtqueue in consistent state in case of error.
> >>>
> >>> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
> >>> ---
> >>>
> >>> Actually, current virtio implementation looks broken for me. Because
> >>> 'virtio_dev_start' breaks virtqueue while it still available from the vhost
> >>> side.
> >>>
> >>> There was 2 patches about this behaviour:
> >>>
> >>> 1. a85786dc816f ("virtio: fix states handling during initialization")
> >>> 2. 9a0615af7746 ("virtio: fix restart")
> >>>
> >>> The second patch fixes somehow issue intoduced in the first patch, but actually
> >>> also breaks vhost in the way described above.
> >>> It's not pretty clear for me what to do in current situation with virtio,
> >>> because it will be broken for guest application even if vhost will not crash.
> >>>
> >>> May be it'll be better to forbid stopping of virtio device and force user to
> >>> exit and start again (may be implemented in hidden from user way)?
> >>>
> >>> This patch adds additional sane checks, so it should be applied anyway, IMHO.
> >>
> >> Agreed.
> >>
> >> --yliu
> >>
> >>
next prev parent reply other threads:[~2016-05-30 14:23 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-20 12:50 Ilya Maximets
2016-05-23 10:57 ` Yuanhan Liu
2016-05-23 11:04 ` Ilya Maximets
2016-05-30 11:05 ` Ilya Maximets
2016-05-30 14:25 ` Yuanhan Liu [this message]
2016-05-31 9:12 ` Ilya Maximets
2016-05-30 12:00 ` Tan, Jianfeng
2016-05-30 12:24 ` Ilya Maximets
2016-05-31 6:53 ` Tan, Jianfeng
2016-05-31 9:10 ` Ilya Maximets
2016-05-31 22:06 ` Rich Lane
2016-06-02 10:46 ` Ilya Maximets
2016-06-02 16:22 ` Rich Lane
2016-06-03 6:01 ` Ilya Maximets
2016-07-01 7:35 ` Yuanhan Liu
2016-07-06 11:19 ` Ilya Maximets
2016-07-06 12:24 ` Yuanhan Liu
2016-07-08 11:48 ` Ilya Maximets
2016-07-10 13:17 ` Yuanhan Liu
2016-07-11 8:38 ` Yuanhan Liu
2016-07-11 9:50 ` Ilya Maximets
2016-07-11 11:05 ` Yuanhan Liu
2016-07-11 11:47 ` Ilya Maximets
2016-07-12 2:43 ` Yuanhan Liu
2016-07-12 5:53 ` Ilya Maximets
2016-07-13 7:34 ` Ilya Maximets
2016-07-13 8:47 ` Yuanhan Liu
2016-07-13 15:54 ` Rich Lane
2016-07-14 1:42 ` Yuanhan Liu
2016-07-14 4:38 ` Ilya Maximets
2016-07-14 8:18 ` [dpdk-dev] [PATCH v2] " Ilya Maximets
2016-07-15 6:17 ` Yuanhan Liu
2016-07-15 7:23 ` Ilya Maximets
2016-07-15 8:40 ` Yuanhan Liu
2016-07-15 11:15 ` [dpdk-dev] [PATCH v3 0/2] " Ilya Maximets
2016-07-15 11:15 ` [dpdk-dev] [PATCH v3 1/2] vhost: fix using of bad return value on mergeable enqueue Ilya Maximets
2016-07-15 11:15 ` [dpdk-dev] [PATCH v3 2/2] vhost: do sanity check for ring descriptor address Ilya Maximets
2016-07-15 12:14 ` [dpdk-dev] [PATCH v3 0/2] vhost: fix segfault on bad " Yuanhan Liu
2016-07-15 19:37 ` Thomas Monjalon
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