[PATCH 2/2] virtio-mmio: Reject invalid IRQ 0 command line argument

[Bjorn Helgaas]

From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

The "virtio_mmio.device=" command line argument allows a user to specify
the size, address, and IRQ of a virtio device.  Previously the only
requirement for the IRQ was that it be an unsigned integer.

Zero is an unsigned integer but an invalid IRQ number, and after
a85a6c86c25be ("driver core: platform: Clarify that IRQ 0 is invalid"),
attempts to use IRQ 0 cause warnings.

If the user specifies IRQ 0, return failure instead of registering a device
with IRQ 0.

Fixes: a85a6c86c25be ("driver core: platform: Clarify that IRQ 0 is invalid")
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
---
 drivers/virtio/virtio_mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 9d16aaffca9d..627ac0487494 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -641,11 +641,11 @@ static int vm_cmdline_set(const char *device,
 			&vm_cmdline_id, &consumed);
 
 	/*
-	 * sscanf() must processes at least 2 chunks; also there
+	 * sscanf() must process at least 2 chunks; also there
 	 * must be no extra characters after the last chunk, so
 	 * str[consumed] must be '\0'
 	 */
-	if (processed < 2 || str[consumed])
+	if (processed < 2 || str[consumed] || irq == 0)
 		return -EINVAL;
 
 	resources[0].flags = IORESOURCE_MEM;
-- 
2.25.1