block/virtio-blk: Fix memory leak from virtio_blk_zone_report

This modification ensures that in scenarios where the buffer size is
insufficient for a zone report, the function will now properly set an
error status and proceed to a cleanup label, instead of merely
returning.

The following ASAN log reveals it:

==1767400==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 312 byte(s) in 1 object(s) allocated from:
    #0 0x64ac7b3280cd in malloc llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:129:3
    #1 0x735b02fb9738 in g_malloc (/lib/x86_64-linux-gnu/libglib-2.0.so.0+0x5e738)
    #2 0x64ac7d23be96 in virtqueue_split_pop hw/virtio/virtio.c:1612:12
    #3 0x64ac7d23728a in virtqueue_pop hw/virtio/virtio.c:1783:16
    #4 0x64ac7cfcaacd in virtio_blk_get_request hw/block/virtio-blk.c:228:27
    #5 0x64ac7cfca7c7 in virtio_blk_handle_vq hw/block/virtio-blk.c:1123:23
    #6 0x64ac7cfecb95 in virtio_blk_handle_output hw/block/virtio-blk.c:1157:5

Signed-off-by: Zheyu Ma <[email protected]>
Message-id: [email protected]
Signed-off-by: Stefan Hajnoczi <[email protected]>

hw/block/virtio-blk.c

@@ -768,7 +768,8 @@ static void virtio_blk_handle_zone_report(VirtIOBlockReq *req,
             sizeof(struct virtio_blk_zone_report) +
             sizeof(struct virtio_blk_zone_descriptor)) {
         virtio_error(vdev, "in buffer too small for zone report");
-        return;
+        err_status = VIRTIO_BLK_S_ZONE_INVALID_CMD;
+        goto out;
     }
 
     /* start byte offset of the zone report */