netdev - Re: [PATCH] netdevsim: Fix memory leak of nsim_dev->fa

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Date:   Tue, 15 Nov 2022 11:38:26 +0800
From:   wangyufen <wangyufen@...wei.com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     <netdev@...r.kernel.org>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <pabeni@...hat.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH] netdevsim: Fix memory leak of nsim_dev->fa_cookie


在 2022/11/15 10:50, Jakub Kicinski 写道:
> On Sat, 12 Nov 2022 14:28:05 +0800 Wang Yufen wrote:
>> nsim_dev_trap_fa_cookie_write()
>>    kmalloc() fa_cookie
>>    nsim_dev->fa_cookie = fa_cookie
>> ..
>> nsim_drv_remove()
>>
>> nsim_dev->fa_cookie alloced, but the nsim_dev_trap_report_work()
>> job has not been done, the flow action cookie has not been assigned
>> to the metadata. To fix, add kfree(nsim_dev->fa_cookie) to
>> nsim_drv_remove().
> I don't see the path thru nsim_dev_trap_report_work() which would free
> the fa_cookie.
>
> The fix looks right, but the commit message seems incorrect. Isn't the
> leak always there, without any race?

Sorry, I didn't make it clear.

The detailed process of nsim_dev_trap_report_work() is as follows:

nsim_dev_trap_report_work()
   nsim_dev_trap_report_work()
     ...
     devlink_trap_report()
       devlink_trap_report_metadata_set()
       <-- fa_cookie is assigned to metadata->fa_cookie here， and will be freed in net_dm_hw_metadata_free()