If vring doesn't use the DMA API, KMSAN is unable to tell whether the
memory is initialized by hardware. Explicitly call kmsan_handle_dma()
from vring_map_one_sg() in this case to prevent false positives.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
Change-Id: Icc8678289b7084139320fc503898a67aa9803458
---
drivers/virtio/virtio_ring.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a8041e451e9e..2f8da5eeb3a0 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/dma-mapping.h>
+#include <linux/kmsan-checks.h>
#include <xen/xen.h>
#ifdef DEBUG
@@ -326,8 +327,15 @@ static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
struct scatterlist *sg,
enum dma_data_direction direction)
{
- if (!vq->use_dma_api)
+ if (!vq->use_dma_api) {
+ /*
+ * If DMA is not used, KMSAN doesn't know that the scatterlist
+ * is initialized by the hardware. Explicitly check/unpoison it
+ * depending on the direction.
+ */
+ kmsan_handle_dma(sg_virt(sg), sg->length, direction);
return (dma_addr_t)sg_phys(sg);
+ }
/*
* We can't use dma_map_sg, because we don't use scatterlists in
--
2.24.0.432.g9d3f5f5b63-goog
