netdev - Re: [PATCH net 1/1] netfilter: flowtable: Fix use after free after freeing flow table

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Date:   Tue, 23 Aug 2022 10:56:44 +0300
From:   Paul Blakey <paulb@...dia.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Oz Shlomo <ozsh@...dia.com>, Roi Dayan <roid@...dia.com>,
        netdev@...r.kernel.org, Saeed Mahameed <saeedm@...dia.com>,
        netfilter-devel@...r.kernel.org
Subject: Re: [PATCH net 1/1] netfilter: flowtable: Fix use after free after
 freeing flow table



On 23/08/2022 00:10, Pablo Neira Ayuso wrote:
> Hi Paul,
> 
> On Sun, Aug 21, 2022 at 12:23:39PM +0300, Paul Blakey wrote:
>> Hi!
>>
>> The only functional difference here (for HW table) is your patches call
>> flush just for the del workqueue instead of del/stats/add, right?
>>
>> Because in the end you do:
>> cancel_delayed_work_sync(&flow_table->gc_work);
>> nf_flow_table_offload_flush(flow_table);
>> nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
>> nf_flow_table_gc_run(flow_table);
>> nf_flow_table_offload_flush_cleanup(flow_table);
>>
>>
>> resulting in the following sequence (after expending flush_cleanup()):
>>
>> cancel_delayed_work_sync(&flow_table->gc_work);
>> nf_flow_table_offload_flush(flow_table);
>> nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
>> nf_flow_table_gc_run(flow_table);
>> flush_workqueue(nf_flow_offload_del_wq);
>> nf_flow_table_gc_run(flowtable);
>>
>>
>> Where as my (and Volodymyr's) patch does:
>>
>> cancel_delayed_work_sync(&flow_table->gc_work);
>> nf_flow_table_offload_flush(flow_table);
>> nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
>> nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, NULL);
>> nf_flow_table_offload_flush(flow_table);
>> nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step, NULL);
>>
>>
>> so almost identical, I don't see "extra reiterative calls to flush" here,
>> but I'm fine with just your patch as it's more efficient, can we take yours
>> to both gits?
> 
> Yes, I'll submit them. I'll re-use your patch description.
> 
> Maybe I get a Tested-by: tag from you?
> 
> Thanks!

Sure I'll test and post.
Thanks.