[PATCH 4.18 092/123] s390/pci: fix out of bounds access during irq setup

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sebastian Ott <sebott@xxxxxxxxxxxxx>

commit 866f3576a72b2233a76dffb80290f8086dc49e17 upstream.

During interrupt setup we allocate interrupt vectors, walk the list of msi
descriptors, and fill in the message data. Requesting more interrupts than
supported on s390 can lead to an out of bounds access.

When we restrict the number of interrupts we should also stop walking the
msi list after all supported interrupts are handled.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/s390/pci/pci.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -421,6 +421,8 @@ int arch_setup_msi_irqs(struct pci_dev *
 	hwirq = 0;
 	for_each_pci_msi_entry(msi, pdev) {
 		rc = -EIO;
+		if (hwirq >= msi_vecs)
+			break;
 		irq = irq_alloc_desc(0);	/* Alloc irq on node 0 */
 		if (irq < 0)
 			return -ENOMEM;