On 08/18/2017 02:41 PM, Joe Stringer wrote:
On 16 August 2017 at 15:48, Greg Rose <[email protected]> wrote:
> Upstream commit:
> commit 494bea39f3201776cdfddc232705f54a0bd210c4
> Author: Liping Zhang <[email protected]>
> Date: Wed Aug 16 13:30:07 2017 +0800
>
> For sw_flow_actions, the actions_len only represents the kernel part's
> size, and when we dump the actions to the userspace, we will do the
> convertions, so it's true size may become bigger than the actions_len.
>
> But unfortunately, for OVS_PACKET_ATTR_ACTIONS, we use the actions_len
> to alloc the skbuff, so the user_skb's size may become insufficient and
> oops will happen like this:
> skbuff: skb_over_panic: text:ffffffff8148fabf len:1749 put:157 head:
> ffff881300f39000 data:ffff881300f39000 tail:0x6d5 end:0x6c0 dev:<NULL>
> ------------[ cut here ]------------
> kernel BUG at net/core/skbuff.c:129!
> [...]
> Call Trace:
> <IRQ>
> [<ffffffff8148be82>] skb_put+0x43/0x44
> [<ffffffff8148fabf>] skb_zerocopy+0x6c/0x1f4
> [<ffffffffa0290d36>] queue_userspace_packet+0x3a3/0x448 [openvswitch]
> [<ffffffffa0292023>] ovs_dp_upcall+0x30/0x5c [openvswitch]
> [<ffffffffa028d435>] output_userspace+0x132/0x158 [openvswitch]
> [<ffffffffa01e6890>] ? ip6_rcv_finish+0x74/0x77 [ipv6]
> [<ffffffffa028e277>] do_execute_actions+0xcc1/0xdc8 [openvswitch]
> [<ffffffffa028e3f2>] ovs_execute_actions+0x74/0x106 [openvswitch]
> [<ffffffffa0292130>] ovs_dp_process_packet+0xe1/0xfd [openvswitch]
> [<ffffffffa0292b77>] ? key_extract+0x63c/0x8d5 [openvswitch]
> [<ffffffffa029848b>] ovs_vport_receive+0xa1/0xc3 [openvswitch]
> [...]
>
> Also we can find that the actions_len is much little than the orig_len:
> crash> struct sw_flow_actions 0xffff8812f539d000
> struct sw_flow_actions {
> rcu = {
> next = 0xffff8812f5398800,
> func = 0xffffe3b00035db32
> },
> orig_len = 1384,
> actions_len = 592,
> actions = 0xffff8812f539d01c
> }
>
> So as a quick fix, use the orig_len instead of the actions_len to alloc
> the user_skb.
>
> Last, this oops happened on our system running a relative old kernel, but
> the same risk still exists on the mainline, since we use the wrong
> actions_len from the beginning.
>
> Fixes: 0e469d3b380c ("datapath: include datapath actions with
sampled-"...)
> Cc: Neil McKee <[email protected]>
> Signed-off-by: Liping Zhang <[email protected]>
> Acked-by: Pravin B Shelar <[email protected]>
> Signed-off-by: David S. Miller <[email protected]>
>
> Signed-off-by: Greg Rose <[email protected]>
> ---
Thanks for the backport.
It seems like we're a bit diverged from the latest net-next, if I
follow correctly these patches haven't been backported yet. Would you
mind preparing these, too?
0ed80da518a1 openvswitch: Remove unnecessary newlines from OVS_NLERR uses
c4b2bf6b4a35 openvswitch: Optimize operations for OvS flow_stats.
c57c054eb5b1 openvswitch: Optimize updating for OvS flow_stats.
880388aa3c07 net: Remove all references to SKB_GSO_UDP.
I realise that this particular patch is a long-standing bug that we
can fix (and will need backporting in our tree), but it's nice if we
can keep the patches applied to master here in the same order as
upstream net-next so that it's easier to tell how out of sync we are
by a side-by-side comparison of "git log --oneline" for datapath/ or
net/openvswitch in the corresponding trees. I also realise that this
patch didn't land in net-next yet since it's so new, but it's fairly
safe to assume it'll be applied there next.
Cheers,
Joe
OK - I had been waiting for patches to hit the net tree before backporting.
I'll get the ones in net-next too and submit a patch series.
Thanks,
- Greg
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