[PATCH 2/2] libvduse: Fix pointer arithmetic in indirect read

[Temir Zharaspayev <masscry@gmail.com>]

When zero-copy usage of indirect descriptors buffer table isn't
possible, library gather scattered memory chunks in a local copy.
This commit fixes the issue with pointer arithmetic for the local copy
buffer.

Signed-off-by: Temir Zharaspayev <masscry@gmail.com>
---
 subprojects/libvduse/libvduse.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/subprojects/libvduse/libvduse.c b/subprojects/libvduse/libvduse.c
index 21ffbb5b8d..0b445fbc76 100644
--- a/subprojects/libvduse/libvduse.c
+++ b/subprojects/libvduse/libvduse.c
@@ -465,7 +465,7 @@ static int
 vduse_queue_read_indirect_desc(VduseDev *dev, struct vring_desc *desc,
                                uint64_t addr, size_t len)
 {
-    struct vring_desc *ori_desc;
+    uint8_t *src_cursor, *dst_cursor;
     uint64_t read_len;
 
     if (len > (VIRTQUEUE_MAX_SIZE * sizeof(struct vring_desc))) {
@@ -476,17 +476,18 @@ vduse_queue_read_indirect_desc(VduseDev *dev, struct vring_desc *desc,
         return -1;
     }
 
+    dst_cursor = (uint8_t *) desc;
     while (len) {
         read_len = len;
-        ori_desc = iova_to_va(dev, &read_len, addr);
-        if (!ori_desc) {
+        src_cursor = iova_to_va(dev, &read_len, addr);
+        if (!src_cursor) {
             return -1;
         }
 
-        memcpy(desc, ori_desc, read_len);
+        memcpy(dst_cursor, src_cursor, read_len);
         len -= read_len;
         addr += read_len;
-        desc += read_len;
+        dst_cursor += read_len;
     }
 
     return 0;
-- 
2.34.1