[PATCH 1/1] s390/pci: fix out of bounds access during irq setup

[Kleber Sacilotto de Souza]

From: Sebastian Ott <sebott at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1790480

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 at vger.kernel.org
Signed-off-by: Sebastian Ott <sebott at linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens at de.ibm.com>
(cherry picked from commit 866f3576a72b2233a76dffb80290f8086dc49e17)
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
---
 arch/s390/pci/pci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 4902fed221c0..8a505cfdd9b9 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -421,6 +421,8 @@ int arch_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 	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;
-- 
2.17.1