Date:   Thu, 2 Feb 2023 10:25:17 +0200
From:   Leon Romanovsky <leon@kernel.org>
To:     Haiyang Zhang <haiyangz@microsoft.com>
Cc:     linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
        decui@microsoft.com, kys@microsoft.com, paulros@microsoft.com,
        olaf@aepfle.de, vkuznets@redhat.com, davem@davemloft.net,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH net,v2] net: mana: Fix accessing freed irq affinity_hint
Message-ID: <Y9tzbZDZmVoFV2bx@unreal>
References: <1675288013-2481-1-git-send-email-haiyangz@microsoft.com>
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On Wed, Feb 01, 2023 at 01:46:53PM -0800, Haiyang Zhang wrote:
> After calling irq_set_affinity_and_hint(), the cpumask pointer is
> saved in desc->affinity_hint, and will be used later when reading
> /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> persistent. Otherwise, we are accessing freed memory when reading
> the affinity_hint file.
> 
> Also, need to clear affinity_hint before free_irq(), otherwise there
> is a one-time warning and stack trace during module unloading:
> 
>  [  243.948687] WARNING: CPU: 10 PID: 1589 at kernel/irq/manage.c:1913 free_irq+0x318/0x360
>  ...
>  [  243.948753] Call Trace:
>  [  243.948754]  <TASK>
>  [  243.948760]  mana_gd_remove_irqs+0x78/0xc0 [mana]
>  [  243.948767]  mana_gd_remove+0x3e/0x80 [mana]
>  [  243.948773]  pci_device_remove+0x3d/0xb0
>  [  243.948778]  device_remove+0x46/0x70
>  [  243.948782]  device_release_driver_internal+0x1fe/0x280
>  [  243.948785]  driver_detach+0x4e/0xa0
>  [  243.948787]  bus_remove_driver+0x70/0xf0
>  [  243.948789]  driver_unregister+0x35/0x60
>  [  243.948792]  pci_unregister_driver+0x44/0x90
>  [  243.948794]  mana_driver_exit+0x14/0x3fe [mana]
>  [  243.948800]  __do_sys_delete_module.constprop.0+0x185/0x2f0
> 
> To fix the bug, use the persistent mask, cpumask_of(cpu#), and set
> affinity_hint to NULL before freeing the IRQ, as required by free_irq().
> 
> Cc: stable@vger.kernel.org
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  .../net/ethernet/microsoft/mana/gdma_main.c   | 35 ++++++-------------
>  1 file changed, 10 insertions(+), 25 deletions(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>