diff --git a/block.c b/block.c
index 50ec5895874cd471918ff24604609f6b2a90e53a..b3d2f120907f44e2073a148e50acf77fceda7bf6 100644
--- a/block.c
+++ b/block.c
@@ -1265,7 +1265,7 @@ static void bdrv_aio_rw_vector_cb(void *opaque, int ret)
     VectorTranslationState *s = opaque;
 
     if (!s->is_write) {
-        qemu_iovec_from_buffer(s->iov, s->bounce);
+        qemu_iovec_from_buffer(s->iov, s->bounce, s->iov->size);
     }
     qemu_free(s->bounce);
     s->this_aiocb->cb(s->this_aiocb->opaque, ret);
diff --git a/cutils.c b/cutils.c
index 80a7a1d8f09354ae9ce4e845a9a6f0656af2a735..1090aa4c77d4590ff55d22d8b992e8bb33774840 100644
--- a/cutils.c
+++ b/cutils.c
@@ -109,6 +109,7 @@ void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
     qiov->iov = qemu_malloc(alloc_hint * sizeof(struct iovec));
     qiov->niov = 0;
     qiov->nalloc = alloc_hint;
+    qiov->size = 0;
 }
 
 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
@@ -119,6 +120,7 @@ void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
     }
     qiov->iov[qiov->niov].iov_base = base;
     qiov->iov[qiov->niov].iov_len = len;
+    qiov->size += len;
     ++qiov->niov;
 }
 
@@ -138,13 +140,18 @@ void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf)
     }
 }
 
-void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf)
+void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count)
 {
     const uint8_t *p = (const uint8_t *)buf;
+    size_t copy;
     int i;
 
-    for (i = 0; i < qiov->niov; ++i) {
-        memcpy(qiov->iov[i].iov_base, p, qiov->iov[i].iov_len);
-        p += qiov->iov[i].iov_len;
+    for (i = 0; i < qiov->niov && count; ++i) {
+        copy = count;
+        if (copy > qiov->iov[i].iov_len)
+            copy = qiov->iov[i].iov_len;
+        memcpy(qiov->iov[i].iov_base, p, copy);
+        p     += copy;
+        count -= copy;
     }
 }
diff --git a/qemu-common.h b/qemu-common.h
index ae773e05db9a26c5e4ba2b6bd53f93936285ca55..42d5e4966e52a8715e70cdd4f9f39c5fb4427366 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -195,13 +195,14 @@ typedef struct QEMUIOVector {
     struct iovec *iov;
     int niov;
     int nalloc;
+    size_t size;
 } QEMUIOVector;
 
 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
 void qemu_iovec_destroy(QEMUIOVector *qiov);
 void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf);
-void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf);
+void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count);
 
 #endif /* dyngen-exec.h hack */