vhost: fix length for cross region descriptor

commit bd97120fc3d1a11f3124c7c9ba1d91f51829eb85 upstream.

If a single descriptor crosses a region, the
second chunk length should be decremented
by size translated so far, instead it includes
the full descriptor length.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 51e4c1eeec4f0b09af84b5feb58c63313cd7d0cb..1a9e2a9b8560dbb92d29c219dbe9ce524d6e86d8 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1074,7 +1074,7 @@ static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
                }
                _iov = iov + ret;
                size = reg->memory_size - addr + reg->guest_phys_addr;
-               _iov->iov_len = min((u64)len, size);
+               _iov->iov_len = min((u64)len - s, size);
                _iov->iov_base = (void __user *)(unsigned long)
                        (reg->userspace_addr + addr - reg->guest_phys_addr);
                s += size;