[PATCH 5/8] vop: vringh: Do not crash if no DMA channel

Vincent Whitchurch
2019-01-16T16:33:08Z

Fallback gracefully if no DMA channel is provided instead of
dereferencing NULL pointers.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
drivers/misc/mic/vop/vop_vringh.c | 32 +++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/misc/mic/vop/vop_vringh.c b/drivers/misc/mic/vop/vop_vringh.c
index ccdfbb652123..18d6ecff1834 100644
--- a/drivers/misc/mic/vop/vop_vringh.c
+++ b/drivers/misc/mic/vop/vop_vringh.c
@@ -531,12 +531,12 @@ static int vop_virtio_copy_to_user(struct vop_vdev *vdev, void __user *ubuf,
void __iomem *dbuf = vpdev->hw_ops->ioremap(vpdev, daddr, len);
struct vop_vringh *vvr = &vdev->vvr[vr_idx];
struct vop_info *vi = dev_get_drvdata(&vpdev->dev);
- size_t dma_alignment = 1 << vi->dma_ch->device->copy_align;
- bool x200 = is_dma_copy_aligned(vi->dma_ch->device, 1, 1, 1);
+ size_t dma_alignment;
+ bool x200;
size_t dma_offset, partlen;
int err;

- if (!VOP_USE_DMA) {
+ if (!VOP_USE_DMA || !vi->dma_ch) {
if (copy_to_user(ubuf, (void __force *)dbuf, len)) {
err = -EFAULT;
dev_err(vop_dev(vdev), "%s %d err %d\n",
@@ -548,6 +548,9 @@ static int vop_virtio_copy_to_user(struct vop_vdev *vdev, void __user *ubuf,
goto err;
}

+ dma_alignment = 1 << vi->dma_ch->device->copy_align;
+ x200 = is_dma_copy_aligned(vi->dma_ch->device, 1, 1, 1);
+
dma_offset = daddr - round_down(daddr, dma_alignment);
daddr -= dma_offset;
len += dma_offset;
@@ -606,18 +609,23 @@ static int vop_virtio_copy_from_user(struct vop_vdev *vdev, void __user *ubuf,
void __iomem *dbuf = vpdev->hw_ops->ioremap(vpdev, daddr, len);
struct vop_vringh *vvr = &vdev->vvr[vr_idx];
struct vop_info *vi = dev_get_drvdata(&vdev->vpdev->dev);
- size_t dma_alignment = 1 << vi->dma_ch->device->copy_align;
- bool x200 = is_dma_copy_aligned(vi->dma_ch->device, 1, 1, 1);
+ size_t dma_alignment;
+ bool x200;
size_t partlen;
- bool dma = VOP_USE_DMA;
+ bool dma = VOP_USE_DMA && vi->dma_ch;
int err = 0;

- if (daddr & (dma_alignment - 1)) {
- vdev->tx_dst_unaligned += len;
- dma = false;
- } else if (ALIGN(len, dma_alignment) > dlen) {
- vdev->tx_len_unaligned += len;
- dma = false;
+ if (dma) {
+ dma_alignment = 1 << vi->dma_ch->device->copy_align;
+ x200 = is_dma_copy_aligned(vi->dma_ch->device, 1, 1, 1);
+
+ if (daddr & (dma_alignment - 1)) {
+ vdev->tx_dst_unaligned += len;
+ dma = false;
+ } else if (ALIGN(len, dma_alignment) > dlen) {
+ vdev->tx_len_unaligned += len;
+ dma = false;
+ }
}

if (!dma)
--
2.20.0