iwlwifi: pcie: compare with number of IRQs requested for, not number of CPUs

When there are 16 or more logical CPUs, we request for
`IWL_MAX_RX_HW_QUEUES` (16) IRQs only as we limit to that number of
IRQs, but later on we compare the number of IRQs returned to
nr_online_cpus+2 instead of max_irqs, the latter being what we
actually asked for. This ends up setting num_rx_queues to 17 which
causes lots of out-of-bounds array accesses later on.

Compare to max_irqs instead, and also add an assertion in case
num_rx_queues > IWM_MAX_RX_HW_QUEUES.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=199551

Fixes: 2e5d4a8f ("iwlwifi: pcie: Add new configuration to enable MSIX")
Signed-off-by: Hao Wei Tee <angelsl@in04.sg>
Tested-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -1590,14 +1590,13 @@ static void iwl_pcie_set_interrupt_capa(struct pci_dev *pdev,
 					struct iwl_trans *trans)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
-	int max_irqs, num_irqs, i, ret, nr_online_cpus;
+	int max_irqs, num_irqs, i, ret;
 	u16 pci_cmd;
 
 	if (!trans->cfg->mq_rx_supported)
 		goto enable_msi;
 
-	nr_online_cpus = num_online_cpus();
-	max_irqs = min_t(u32, nr_online_cpus + 2, IWL_MAX_RX_HW_QUEUES);
+	max_irqs = min_t(u32, num_online_cpus() + 2, IWL_MAX_RX_HW_QUEUES);
 	for (i = 0; i < max_irqs; i++)
 		trans_pcie->msix_entries[i].entry = i;
 
@@ -1623,16 +1622,17 @@ static void iwl_pcie_set_interrupt_capa(struct pci_dev *pdev,
 	 * Two interrupts less: non rx causes shared with FBQ and RSS.
 	 * More than two interrupts: we will use fewer RSS queues.
 	 */
-	if (num_irqs <= nr_online_cpus) {
+	if (num_irqs <= max_irqs - 2) {
 		trans_pcie->trans->num_rx_queues = num_irqs + 1;
 		trans_pcie->shared_vec_mask = IWL_SHARED_IRQ_NON_RX |
 			IWL_SHARED_IRQ_FIRST_RSS;
-	} else if (num_irqs == nr_online_cpus + 1) {
+	} else if (num_irqs == max_irqs - 1) {
 		trans_pcie->trans->num_rx_queues = num_irqs;
 		trans_pcie->shared_vec_mask = IWL_SHARED_IRQ_NON_RX;
 	} else {
 		trans_pcie->trans->num_rx_queues = num_irqs - 1;
 	}
+	WARN_ON(trans_pcie->trans->num_rx_queues > IWL_MAX_RX_HW_QUEUES);
 
 	trans_pcie->alloc_vecs = num_irqs;
 	trans_pcie->msix_enabled = true;