From: Jason Wang <jasowang@redhat.com>
Date: Tue, 19 Oct 2021 15:01:43 +0800
Subject: virtio-blk: validate num_queues during probe
Git-commit: 6ae6ff6f6e7d2f304a12a53af8298e4f16ad633e
Patch-mainline: v5.16-rc1
References: jsc#PED-1559

If an untrusted device neogitates BLK_F_MQ but advertises a zero
num_queues, the driver may end up trying to allocating zero size
buffers where ZERO_SIZE_PTR is returned which may pass the checking
against the NULL. This will lead unexpected results.

Fixing this by failing the probe in this case.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20211019070152.8236-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/block/virtio_blk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index a33fe0743672..dbcf2a7e4a00 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -571,6 +571,10 @@ static int init_vq(struct virtio_blk *vblk)
 				   &num_vqs);
 	if (err)
 		num_vqs = 1;
+	if (!err && !num_vqs) {
+		dev_err(&vdev->dev, "MQ advertisted but zero queues reported\n");
+		return -EINVAL;
+	}
 
 	num_vqs = min_t(unsigned int,
 			min_not_zero(num_request_queues, nr_cpu_ids),