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Date:   Mon, 4 Apr 2022 17:01:28 +0200
From:   Ivan Vecera <ivecera@redhat.com>
To:     Alexander Lobakin <alexandr.lobakin@intel.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        Madhu Chittim <madhu.chittim@intel.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        Brett Creeley <brett@pensando.io>,
        intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] ice: arfs: fix use-after-free when freeing
 @rx_cpu_rmap
Message-ID: <20220404170128.1f8d198a@ceranb>
In-Reply-To: <20220404132832.1936529-1-alexandr.lobakin@intel.com>
References: <20220404132832.1936529-1-alexandr.lobakin@intel.com>
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On Mon,  4 Apr 2022 15:28:32 +0200
Alexander Lobakin <alexandr.lobakin@intel.com> wrote:

> The CI testing bots triggered the following splat:
> 
> ...
> This is due to that free_irq_cpu_rmap() is always being called
> *after* (devm_)free_irq() and thus it tries to work with IRQ descs
> already freed. For example, on device reset the driver frees the
> rmap right before allocating a new one (the splat above).
> Make rmap creation and freeing function symmetrical with
> {request,free}_irq() calls i.e. do that on ifup/ifdown instead
> of device probe/remove/resume. These operations can be performed
> independently from the actual device aRFS configuration.
> Also, make sure ice_vsi_free_irq() clears IRQ affinity notifiers
> only when aRFS is disabled -- otherwise, CPU rmap sets and clears
> its own and they must not be touched manually.
> 
> Fixes: 28bf26724fdb0 ("ice: Implement aRFS")
> Co-developed-by: Ivan Vecera <ivecera@redhat.com>
> Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
> ---
> Netdev folks, some more urgent stuff, would like to have this in
> -net directly.
> 
> Ivan, I probably should've waited for your response regarding
> signatures, hope you'll approve this one :p Feel free to review
> and/or test.

That's ok, Alex. You did it the way I prefer :-P.
Will test.

Ivan