Messages in this thread | | | Subject | Re: [PATCH 2/2] virtio/virtio_ring: Fix the dma_max_mapping_size call | From | Robin Murphy <> | Date | Mon, 22 Jul 2019 16:36:09 +0100 |
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On 22/07/2019 15:55, Eric Auger wrote: > 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)
Hmm, might it make sense to roll that check up into vring_use_dma_api() itself? After all, if the device has no mask then it's likely that other DMA API ops wouldn't really work as expected either.
Robin.
> max_segment_size = dma_max_mapping_size(&vdev->dev); > > return max_segment_size; >
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