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[Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn
From: |
Jason Wang |
Subject: |
[Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn |
Date: |
Mon, 13 Mar 2017 14:29:41 +0800 |
To avoid access stale memory region cache after reset, this patch
check the existence of virtqueue pfn for all exported virtqueue access
helpers before trying to use them.
Cc: Cornelia Huck <address@hidden>
Cc: Paolo Bonzini <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
hw/virtio/virtio.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index efce4b3..76cc81b 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -322,6 +322,10 @@ static int virtio_queue_empty_rcu(VirtQueue *vq)
return 0;
}
+ if (unlikely(!vq->vring.avail)) {
+ return 0;
+ }
+
return vring_avail_idx(vq) == vq->last_avail_idx;
}
@@ -333,6 +337,10 @@ int virtio_queue_empty(VirtQueue *vq)
return 0;
}
+ if (unlikely(!vq->vring.avail)) {
+ return 0;
+ }
+
rcu_read_lock();
empty = vring_avail_idx(vq) == vq->last_avail_idx;
rcu_read_unlock();
@@ -431,6 +439,10 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement
*elem,
return;
}
+ if (unlikely(!vq->vring.used)) {
+ return;
+ }
+
idx = (idx + vq->used_idx) % vq->vring.num;
uelem.id = elem->index;
@@ -448,6 +460,10 @@ void virtqueue_flush(VirtQueue *vq, unsigned int count)
return;
}
+ if (unlikely(!vq->vring.used)) {
+ return;
+ }
+
/* Make sure buffer is written before we update index. */
smp_wmb();
trace_virtqueue_flush(vq, count);
@@ -546,6 +562,11 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int
*in_bytes,
int64_t len = 0;
int rc;
+ if (unlikely(!vq->vring.desc)) {
+ *in_bytes = *out_bytes = 0;
+ return;
+ }
+
rcu_read_lock();
idx = vq->last_avail_idx;
total_bufs = in_total = out_total = 0;
--
2.7.4