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    Subject[PATCH net,v2] net: mana: Fix accessing freed irq affinity_hint
    Date
    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(-)

    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
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