1 files changed, 80 insertions, 12 deletions

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index dd95dfd85e98..00f64f2f8b72 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -14,6 +14,9 @@
 #include <linux/spinlock.h>
 #include <xen/xen.h>
 
+static bool force_used_validation = false;
+module_param(force_used_validation, bool, 0444);
+
 #ifdef DEBUG
 /* For development, we want to crash whenever the ring is screwed. */
 #define BAD_RING(_vq, fmt, args...)				\
@@ -79,8 +82,8 @@ struct vring_desc_state_packed {
 };
 
 struct vring_desc_extra {
-	dma_addr_t addr;		/* Buffer DMA addr. */
-	u32 len;			/* Buffer length. */
+	dma_addr_t addr;		/* Descriptor DMA addr. */
+	u32 len;			/* Descriptor length. */
 	u16 flags;			/* Descriptor flags. */
 	u16 next;			/* The next desc state in a list. */
 };
@@ -182,6 +185,9 @@ struct vring_virtqueue {
 		} packed;
 	};
 
+	/* Per-descriptor in buffer length */
+	u32 *buflen;
+
 	/* How to notify other side. FIXME: commonalize hcalls! */
 	bool (*notify)(struct virtqueue *vq);
 
@@ -490,6 +496,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	unsigned int i, n, avail, descs_used, prev, err_idx;
 	int head;
 	bool indirect;
+	u32 buflen = 0;
 
 	START_USE(vq);
 
@@ -571,12 +578,13 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 						     VRING_DESC_F_NEXT |
 						     VRING_DESC_F_WRITE,
 						     indirect);
+			buflen += sg->length;
 		}
 	}
 	/* Last one doesn't continue. */
 	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 	if (!indirect && vq->use_dma_api)
-		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags =
+		vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &=
 			~VRING_DESC_F_NEXT;
 
 	if (indirect) {
@@ -610,6 +618,10 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
 	else
 		vq->split.desc_state[head].indir_desc = ctx;
 
+	/* Store in buffer length if necessary */
+	if (vq->buflen)
+		vq->buflen[head] = buflen;
+
 	/* Put entry in available array (but don't update avail->idx until they
 	 * do sync). */
 	avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1);
@@ -784,6 +796,11 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
 		BAD_RING(vq, "id %u is not a head!\n", i);
 		return NULL;
 	}
+	if (vq->buflen && unlikely(*len > vq->buflen[i])) {
+		BAD_RING(vq, "used len %d is larger than in buflen %u\n",
+			*len, vq->buflen[i]);
+		return NULL;
+	}
 
 	/* detach_buf_split clears data, so grab it now. */
 	ret = vq->split.desc_state[i].data;
@@ -1050,21 +1067,24 @@ static struct vring_packed_desc *alloc_indirect_packed(unsigned int total_sg,
 }
 
 static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
-				       struct scatterlist *sgs[],
-				       unsigned int total_sg,
-				       unsigned int out_sgs,
-				       unsigned int in_sgs,
-				       void *data,
-				       gfp_t gfp)
+					 struct scatterlist *sgs[],
+					 unsigned int total_sg,
+					 unsigned int out_sgs,
+					 unsigned int in_sgs,
+					 void *data,
+					 gfp_t gfp)
 {
 	struct vring_packed_desc *desc;
 	struct scatterlist *sg;
 	unsigned int i, n, err_idx;
 	u16 head, id;
 	dma_addr_t addr;
+	u32 buflen = 0;
 
 	head = vq->packed.next_avail_idx;
 	desc = alloc_indirect_packed(total_sg, gfp);
+	if (!desc)
+		return -ENOMEM;
 
 	if (unlikely(vq->vq.num_free < 1)) {
 		pr_debug("Can't add buf len 1 - avail = 0\n");
@@ -1089,6 +1109,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 			desc[i].addr = cpu_to_le64(addr);
 			desc[i].len = cpu_to_le32(sg->length);
 			i++;
+			if (n >= out_sgs)
+				buflen += sg->length;
 		}
 	}
 
@@ -1142,6 +1164,10 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 	vq->packed.desc_state[id].indir_desc = desc;
 	vq->packed.desc_state[id].last = id;
 
+	/* Store in buffer length if necessary */
+	if (vq->buflen)
+		vq->buflen[id] = buflen;
+
 	vq->num_added += 1;
 
 	pr_debug("Added buffer head %i to %p\n", head, vq);
@@ -1176,6 +1202,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	unsigned int i, n, c, descs_used, err_idx;
 	__le16 head_flags, flags;
 	u16 head, id, prev, curr, avail_used_flags;
+	int err;
+	u32 buflen = 0;
 
 	START_USE(vq);
 
@@ -1191,9 +1219,14 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 
 	BUG_ON(total_sg == 0);
 
-	if (virtqueue_use_indirect(_vq, total_sg))
-		return virtqueue_add_indirect_packed(vq, sgs, total_sg,
-				out_sgs, in_sgs, data, gfp);
+	if (virtqueue_use_indirect(_vq, total_sg)) {
+		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
+						    in_sgs, data, gfp);
+		if (err != -ENOMEM)
+			return err;
+
+		/* fall back on direct */
+	}
 
 	head = vq->packed.next_avail_idx;
 	avail_used_flags = vq->packed.avail_used_flags;
@@ -1250,6 +1283,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 					1 << VRING_PACKED_DESC_F_AVAIL |
 					1 << VRING_PACKED_DESC_F_USED;
 			}
+			if (n >= out_sgs)
+				buflen += sg->length;
 		}
 	}
 
@@ -1269,6 +1304,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 	vq->packed.desc_state[id].indir_desc = ctx;
 	vq->packed.desc_state[id].last = prev;
 
+	/* Store in buffer length if necessary */
+	if (vq->buflen)
+		vq->buflen[id] = buflen;
+
 	/*
 	 * A driver MUST NOT make the first descriptor in the list
 	 * available before all subsequent descriptors comprising
@@ -1455,6 +1494,11 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
 		BAD_RING(vq, "id %u is not a head!\n", id);
 		return NULL;
 	}
+	if (vq->buflen && unlikely(*len > vq->buflen[id])) {
+		BAD_RING(vq, "used len %d is larger than in buflen %u\n",
+			*len, vq->buflen[id]);
+		return NULL;
+	}
 
 	/* detach_buf_packed clears data, so grab it now. */
 	ret = vq->packed.desc_state[id].data;
@@ -1660,6 +1704,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	struct vring_virtqueue *vq;
 	struct vring_packed_desc *ring;
 	struct vring_packed_desc_event *driver, *device;
+	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
 	size_t ring_size_in_bytes, event_size_in_bytes;
 
@@ -1749,6 +1794,15 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	if (!vq->packed.desc_extra)
 		goto err_desc_extra;
 
+	if (!drv->suppress_used_validation || force_used_validation) {
+		vq->buflen = kmalloc_array(num, sizeof(*vq->buflen),
+					   GFP_KERNEL);
+		if (!vq->buflen)
+			goto err_buflen;
+	} else {
+		vq->buflen = NULL;
+	}
+
 	/* No callback?  Tell other side not to bother us. */
 	if (!callback) {
 		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
@@ -1761,6 +1815,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	spin_unlock(&vdev->vqs_list_lock);
 	return &vq->vq;
 
+err_buflen:
+	kfree(vq->packed.desc_extra);
 err_desc_extra:
 	kfree(vq->packed.desc_state);
 err_desc_state:
@@ -2168,6 +2224,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 					void (*callback)(struct virtqueue *),
 					const char *name)
 {
+	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 	struct vring_virtqueue *vq;
 
 	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
@@ -2227,6 +2284,15 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 	if (!vq->split.desc_extra)
 		goto err_extra;
 
+	if (!drv->suppress_used_validation || force_used_validation) {
+		vq->buflen = kmalloc_array(vring.num, sizeof(*vq->buflen),
+					   GFP_KERNEL);
+		if (!vq->buflen)
+			goto err_buflen;
+	} else {
+		vq->buflen = NULL;
+	}
+
 	/* Put everything in free lists. */
 	vq->free_head = 0;
 	memset(vq->split.desc_state, 0, vring.num *
@@ -2237,6 +2303,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
 	spin_unlock(&vdev->vqs_list_lock);
 	return &vq->vq;
 
+err_buflen:
+	kfree(vq->split.desc_extra);
 err_extra:
 	kfree(vq->split.desc_state);
 err_state: