Re: [PATCH] scsi: mpt3sas: avoid out-of-bounds cpumask_of_node() call in _base_assign_reply_queues()

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Incorrect calculation of remaining MSI-X queues causes a Division by Zero kernel panic or severe IO imbalance.
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--- Patch [1]: [PATCH] scsi: mpt3sas: avoid out-of-bounds cpumask_of_node() call in _base_assign_reply_queues() ---
commit 2577a38cb04664cd3aa266df2234da5f8d4aff10
Author: Ivy Lopez <[email protected]>

scsi: mpt3sas: avoid out-of-bounds cpumask_of_node() call in _base_assign_reply_queues()

Fixes an out-of-bounds array read in cpumask_of_node() by checking if
dev_to_node() returns NUMA_NO_NODE. If so, it falls back to cpu_online_mask
instead of using the invalid NUMA node index.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221294

> diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
> index fed7aeffec58d..b354cbcd12741 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_base.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
> @@ -3238,7 +3238,9 @@ _base_assign_reply_queues(struct MPT3SAS_ADAPTER *ioc)
>  		 * corresponding to high iops queues.
>  		 */
>  		if (ioc->high_iops_queues) {
> -			mask = cpumask_of_node(dev_to_node(&ioc->pdev->dev));
> +			int node = (dev_to_node(&ioc->pdev->dev));
> +
> +			mask = (node == NUMA_NO_NODE) ? cpu_online_mask : cpumask_of_node(node);
>  			for (index = 0; index < ioc->high_iops_queues;
>  			    index++) {
>  				irq = pci_irq_vector(ioc->pdev, index);

[ ... ]

[Severity: High]
This is a pre-existing issue, but I noticed a potential division by zero
later in drivers/scsi/mpt3sas/mpt3sas_base.c:_base_assign_reply_queues():

fall_back:
	cpu = cpumask_first(cpu_online_mask);
	nr_msix -= (ioc->high_iops_queues - iopoll_q_count);
	index = 0;

	list_for_each_entry(reply_q, &ioc->reply_queue_list, list) {
		unsigned int i, group = nr_cpus / nr_msix;

Can this result in a division by zero panic?

If iopoll_q_count == 0 and all available vectors are assigned to
high_iops_queues, nr_msix becomes 0. The list loop unconditionally computes
group = nr_cpus / nr_msix before checking if the queue is a default queue,
triggering a division by zero.

Additionally, does the fallback logic incorrectly add the poll queues instead
of subtracting them when iopoll_q_count > 0? This would shrink the CPU group
size and could cause unassigned CPUs to fall back to a single queue.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1