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From: Eric Auger <eric.auger@redhat.com>
To: eric.auger.pro@gmail.com, eric.auger@redhat.com, hch@lst.de,
	m.szyprowski@samsung.com, robin.murphy@arm.com, mst@redhat.com,
	jasowang@redhat.com, virtualization@lists.linux-foundation.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/2] virtio/virtio_ring: Fix the dma_max_mapping_size call
Date: Mon, 22 Jul 2019 16:55:09 +0200	[thread overview]
Message-ID: <20190722145509.1284-3-eric.auger@redhat.com> (raw)
In-Reply-To: <20190722145509.1284-1-eric.auger@redhat.com>

Do not call dma_max_mapping_size for devices that have no DMA
mask set, otherwise we can hit a NULL pointer dereference.

This occurs when a virtio-blk-pci device is protected with
a virtual IOMMU.

Fixes: e6d6dd6c875e ("virtio: Introduce virtio_max_dma_size()")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
---
 drivers/virtio/virtio_ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index c8be1c4f5b55..37c143971211 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -262,7 +262,7 @@ size_t virtio_max_dma_size(struct virtio_device *vdev)
 {
 	size_t max_segment_size = SIZE_MAX;
 
-	if (vring_use_dma_api(vdev))
+	if (vring_use_dma_api(vdev) && vdev->dev.dma_mask)
 		max_segment_size = dma_max_mapping_size(&vdev->dev);
 
 	return max_segment_size;
-- 
2.20.1


  parent reply	other threads:[~2019-07-22 14:55 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-22 14:55 [PATCH 0/2] Fix NULL pointer dereference with virtio-blk-pci and virtual IOMMU Eric Auger
2019-07-22 14:55 ` [PATCH 1/2] dma-mapping: Protect dma_addressing_limited against NULL dma_mask Eric Auger
2019-07-22 15:26   ` Christoph Hellwig
2019-07-22 15:46     ` Auger Eric
2019-07-22 14:55 ` Eric Auger [this message]
2019-07-22 15:27   ` [PATCH 2/2] virtio/virtio_ring: Fix the dma_max_mapping_size call Christoph Hellwig
2019-07-22 15:39     ` Michael S. Tsirkin
2019-07-22 15:33   ` Michael S. Tsirkin
2019-07-23 15:38     ` Christoph Hellwig
2019-07-23 15:47       ` Michael S. Tsirkin
2019-07-22 15:36   ` Robin Murphy
2019-07-22 15:45     ` Michael S. Tsirkin
2019-07-23 15:38     ` Christoph Hellwig
2019-07-24 22:10       ` Michael S. Tsirkin
2019-07-25  5:25         ` Christoph Hellwig
2019-07-25 11:53       ` Auger Eric
2019-07-25 13:04         ` Christoph Hellwig
2019-07-25 16:32           ` Auger Eric

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