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

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Message-ID: <aaa31105-6b1a-c026-ab26-00b6b99094b1@nvidia.com>
Date:   Tue, 23 Aug 2022 12:49:01 +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 10:56, Paul Blakey wrote:
> 
> 
> 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.

Tested-By: Paul Blakey <paulb@...dia.com>

Works, thanks.