[libvirt PATCH v2] qemu_command: fix FD usage in qemuBuildInterfaceCommandLine

[Pavel Hrdina <phrdina@xxxxxxxxxx>]

If virCommandPassFD() is called with VIR_COMMAND_PASS_FD_CLOSE_PARENT
the passed FD is closed. If qemuVirCommandGetFDSet() returns NULL we
would jump to cleanup where the vdpafd is closed again if not set to -1.

In order to fix it use a different variable where we will copy FD
number.

Signed-off-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
---
 src/qemu/qemu_command.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 0eec35da16..2a786e34dd 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -8141,18 +8141,20 @@ qemuBuildInterfaceCommandLine(virQEMUDriverPtr driver,
     if (vdpafd > 0) {
         g_autofree char *fdset = NULL;
         g_autofree char *addfdarg = NULL;
+        int vdpafd_copy = vdpafd;
 
         virCommandPassFD(cmd, vdpafd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
-        fdset = qemuVirCommandGetFDSet(cmd, vdpafd);
+        vdpafd = -1;
+
+        fdset = qemuVirCommandGetFDSet(cmd, vdpafd_copy);
         if (!fdset)
             goto cleanup;
-        vdpafdName = qemuVirCommandGetDevSet(cmd, vdpafd);
+        vdpafdName = qemuVirCommandGetDevSet(cmd, vdpafd_copy);
         /* set opaque to the devicepath so that we can look up the fdset later
          * if necessary */
         addfdarg = g_strdup_printf("%s,opaque=%s", fdset,
                                    net->data.vdpa.devicepath);
         virCommandAddArgList(cmd, "-add-fd", addfdarg, NULL);
-        vdpafd = -1;
     }
 
     if (chardev)
-- 
2.26.2