[PATCH 5/7] s390/pci: add NULL check in zpci_msi_clear_airq()

[Tobias Schumacher]

zpci_msi_clear_airq() clears IRQ data in both DIRECTED and FLOATING
modes but does not check if the interrupt vector pointers are NULL
before dereferencing them.

In DIRECTED mode, zpci_ibv[cpu] can be NULL if:
- zpci_directed_irq_init() fails during boot after allocating some
  but not all per-CPU vectors, and cleanup is attempted
- The system is shutting down and zpci_irq_exit() has already
  released some vectors

In FLOATING mode, zdev->aibv can be NULL if:
- zpci_msi_prepare() fails after __alloc_airq() but before setting
  up the device's AIBV, and zpci_msi_domain_free() is called during
  error cleanup
- The device is being torn down and zpci_msi_teardown_floating()
  has already released the AIBV

Add NULL checks for zpci_ibv[cpu] in DIRECTED mode and zdev->aibv in
FLOATING mode to prevent crashes during these error and shutdown paths.

Fixes: f770950a4709 ("s390/pci: Migrate s390 IRQ logic to IRQ domain API")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tobias Schumacher <ts@xxxxxxxxxxxxx>
---
 arch/s390/pci/pci_irq.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/s390/pci/pci_irq.c b/arch/s390/pci/pci_irq.c
index e9eda846cb2d..1515d8d7460e 100644
--- a/arch/s390/pci/pci_irq.c
+++ b/arch/s390/pci/pci_irq.c
@@ -465,12 +465,16 @@ static void zpci_msi_clear_airq(struct irq_data *d, int i)
 
 	if (irq_delivery == DIRECTED) {
 		for_each_possible_cpu(cpu) {
-			airq_iv_set_ptr(zpci_ibv[cpu], bit + i, 0);
-			airq_iv_set_data(zpci_ibv[cpu], bit + i, 0);
+			if (zpci_ibv[cpu]) {
+				airq_iv_set_ptr(zpci_ibv[cpu], bit + i, 0);
+				airq_iv_set_data(zpci_ibv[cpu], bit + i, 0);
+			}
 		}
 	} else {
-		airq_iv_set_ptr(zdev->aibv, bit + i, 0);
-		airq_iv_set_data(zdev->aibv, bit + i, 0);
+		if (zdev->aibv) {
+			airq_iv_set_ptr(zdev->aibv, bit + i, 0);
+			airq_iv_set_data(zdev->aibv, bit + i, 0);
+		}
 	}
 }
 

-- 
2.53.0