linux-kernel - RE: [PATCH net,v2] net: mana: Fix accessing freed irq affinity

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Date:   Wed, 1 Feb 2023 22:09:55 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Haiyang Zhang <haiyangz@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Haiyang Zhang <haiyangz@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Paul Rosswurm <paulros@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH net,v2] net: mana: Fix accessing freed irq affinity_hint

From: LKML haiyangz <lkmlhyz@...rosoft.com> On Behalf Of Haiyang Zhang  Sent: Wednesday, February 1, 2023 1:47 PM
> 
> 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@...r.kernel.org
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
> ---
>  .../net/ethernet/microsoft/mana/gdma_main.c   | 35 ++++++-------------
>  1 file changed, 10 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index b144f2237748..a55d42332e20 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1218,8 +1218,6 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  	struct gdma_context *gc = pci_get_drvdata(pdev);
>  	struct gdma_irq_context *gic;
>  	unsigned int max_irqs;
> -	u16 *cpus;
> -	cpumask_var_t req_mask;
>  	int nvec, irq;
>  	int err, i = 0, j;
> 
> @@ -1240,21 +1238,7 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  		goto free_irq_vector;
>  	}
> 
> -	if (!zalloc_cpumask_var(&req_mask, GFP_KERNEL)) {
> -		err = -ENOMEM;
> -		goto free_irq;
> -	}
> -
> -	cpus = kcalloc(nvec, sizeof(*cpus), GFP_KERNEL);
> -	if (!cpus) {
> -		err = -ENOMEM;
> -		goto free_mask;
> -	}
> -	for (i = 0; i < nvec; i++)
> -		cpus[i] = cpumask_local_spread(i, gc->numa_node);
> -
>  	for (i = 0; i < nvec; i++) {
> -		cpumask_set_cpu(cpus[i], req_mask);
>  		gic = &gc->irq_contexts[i];
>  		gic->handler = NULL;
>  		gic->arg = NULL;
> @@ -1269,17 +1253,16 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  		irq = pci_irq_vector(pdev, i);
>  		if (irq < 0) {
>  			err = irq;
> -			goto free_mask;
> +			goto free_irq;
>  		}
> 
>  		err = request_irq(irq, mana_gd_intr, 0, gic->name, gic);
>  		if (err)
> -			goto free_mask;
> -		irq_set_affinity_and_hint(irq, req_mask);
> -		cpumask_clear(req_mask);
> +			goto free_irq;
> +
> +		irq_set_affinity_and_hint(irq, cpumask_of(cpumask_local_spread
> +					  (i, gc->numa_node)));
>  	}
> -	free_cpumask_var(req_mask);
> -	kfree(cpus);
> 
>  	err = mana_gd_alloc_res_map(nvec, &gc->msix_resource);
>  	if (err)
> @@ -1290,13 +1273,12 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> 
>  	return 0;
> 
> -free_mask:
> -	free_cpumask_var(req_mask);
> -	kfree(cpus);
>  free_irq:
>  	for (j = i - 1; j >= 0; j--) {
>  		irq = pci_irq_vector(pdev, j);
>  		gic = &gc->irq_contexts[j];
> +
> +		irq_update_affinity_hint(irq, NULL);
>  		free_irq(irq, gic);
>  	}
> 
> @@ -1324,6 +1306,9 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
>  			continue;
> 
>  		gic = &gc->irq_contexts[i];
> +
> +		/* Need to clear the hint before free_irq */
> +		irq_update_affinity_hint(irq, NULL);
>  		free_irq(irq, gic);
>  	}
> 
> --
> 2.25.1

Reviewed-by: Michael Kelley