Thx Andy for providing the core file. It is very helpful!
The root cause is that:
1. when udpif_flush() is called, it sets both n-handlers and n-revalidators
to 0
2. in refresh_channels() (dpif-linux.c), though the new 'n_handlers = 0',
we still try
dpif->handlers = xzalloc(n_handlers * sizeof *dpif->handlers).
3. 'xzalloc(0)' is equivalent to 'malloc(1)' in ovs. So, 'dpif->handlers'
will point to a
random address of 1 byte. And future dereference will result in
SEGFAULT.
I think a better fix is to check if the new 'n_handlers' is zero,
'dpif->handlers = NULL'.
I'll send out a separate patch.
Thx,
Alex Wang,
On Mon, Apr 21, 2014 at 10:02 AM, Alex Wang <[email protected]> wrote:
> Hey Andy,
>
> Thx for the fix. Could you provide more info on how to reproduce it?
> maybe the backtrace?
>
> I expect vport_del_channels() to be called only when 'port_idx >=
> dpif->uc_array_size' or dpif->handlers[0].channels is non-NULL.
>
> I want to know more about the context.
>
> Thx
> Alex Wang,
>
>
> On Sun, Apr 20, 2014 at 11:47 PM, Andy Zhou <[email protected]> wrote:
>
>> When testing megaflow bond implement I ran into a case where
>> dpif->handler[0].channels is NULL. Indexing into channels causes
>> vswitchd to crash. Not sure this is the best way to fix it, but
>> it worked for me.
>>
>> Signed-off-by: Andy Zhou <[email protected]>
>> ---
>> lib/dpif-linux.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/lib/dpif-linux.c b/lib/dpif-linux.c
>> index a575b78..9ba6e6a 100644
>> --- a/lib/dpif-linux.c
>> +++ b/lib/dpif-linux.c
>> @@ -441,6 +441,10 @@ vport_del_channels(struct dpif_linux *dpif,
>> odp_port_t port_no)
>> return;
>> }
>>
>> + if (!dpif->handlers[0].channels) {
>> + return;
>> + }
>> +
>> /* Since the sock can only be assigned in either all or none
>> * of "dpif->handlers" channels, the following check would
>> * suffice. */
>> --
>> 1.7.9.5
>>
>> _______________________________________________
>> dev mailing list
>> [email protected]
>> http://openvswitch.org/mailman/listinfo/dev
>>
>
>
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