From: LKML haiyangz <lkmlhyz@xxxxxxxxxxxxx> On Behalf Of Haiyang Zhang Sent: Thursday, January 26, 2023 1:05 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
> allocated per irq, and available until freeing the irq. Otherwise,
> we are accessing freed memory when reading the affinity_hint file.
>
> To fix the bug, allocate the cpumask per irq, and free it just
> before freeing the irq.
Since the cpumask being passed to irq_set_affinity_and_hint()
always contains exactly one CPU, the code can be considerably
simplified by using the pre-calculated and persistent masks
available as cpumask_of(cpu). All allocation of cpumasks in this
code goes away, and you can set the affinity_hint to NULL in the
cleanup and remove paths without having to free any masks.
Michael
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes")
> Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> ---
> .../net/ethernet/microsoft/mana/gdma_main.c | 40 ++++++++++---------
> include/net/mana/gdma.h | 1 +
> 2 files changed, 23 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> index 3bae9d4c1f08..37473ae3859c 100644
> --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> @@ -1219,7 +1219,6 @@ static int mana_gd_setup_irqs(struct pci_dev *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;
>
> @@ -1240,25 +1239,26 @@ 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;
> + goto free_gic;
> }
> 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;
>
> + if (!zalloc_cpumask_var(&gic->cpu_hint, GFP_KERNEL)) {
> + err = -ENOMEM;
> + goto free_irq;
> + }
> +
> + cpumask_set_cpu(cpus[i], gic->cpu_hint);
> +
> if (!i)
> snprintf(gic->name, MANA_IRQ_NAME_SZ,
> "mana_hwc@pci:%s",
> pci_name(pdev));
> @@ -1269,17 +1269,18 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> irq = pci_irq_vector(pdev, i);
> if (irq < 0) {
> err = irq;
> - goto free_mask;
> + free_cpumask_var(gic->cpu_hint);
> + 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);
> + if (err) {
> + free_cpumask_var(gic->cpu_hint);
> + goto free_irq;
> + }
> +
> + irq_set_affinity_and_hint(irq, gic->cpu_hint);
> }
> - free_cpumask_var(req_mask);
> - kfree(cpus);
>
> err = mana_gd_alloc_res_map(nvec, &gc->msix_resource);
> if (err)
> @@ -1288,20 +1289,22 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
> gc->max_num_msix = nvec;
> gc->num_msix_usable = nvec;
>
> + kfree(cpus);
> 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_cpumask_var(gic->cpu_hint);
> free_irq(irq, gic);
> }
>
> + kfree(cpus);
> +
> +free_gic:
> kfree(gc->irq_contexts);
> gc->irq_contexts = NULL;
> free_irq_vector:
> @@ -1329,6 +1332,7 @@ static void mana_gd_remove_irqs(struct pci_dev *pdev)
>
> /* Need to clear the hint before free_irq */
> irq_update_affinity_hint(irq, NULL);
> + free_cpumask_var(gic->cpu_hint);
> free_irq(irq, gic);
> }
>
> diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h
> index 56189e4252da..4dcafecbd89e 100644
> --- a/include/net/mana/gdma.h
> +++ b/include/net/mana/gdma.h
> @@ -342,6 +342,7 @@ struct gdma_irq_context {
> void (*handler)(void *arg);
> void *arg;
> char name[MANA_IRQ_NAME_SZ];
> + cpumask_var_t cpu_hint;
> };
>
> struct gdma_context {
> --
> 2.25.1
