[PATCH 2/2] qemuBuildInterfaceConnect: Initialize @tapfd array

[Michal Privoznik]

When creating a TAP interface we can end up with multiple FDs,
each representing one queue. However, these FDs must be
relabelled as they are then passed to QEMU. In case of
qemuBuildInterfaceConnect() we allocate the array for the FDs and
then let function corresponding to the <interface/> type to fill
the array with FDs. When any of the functions meets an error,
it's also responsible for closing previously opened FDs. However,
the functions take a shortcut: iterate through each member of the
array and close it (if it's non-negative). This assumes that the
array is initialized to negative values, which use to be the case
before rewrite in v8.4.0-rc1~170 but after it it's no longer the
case. Subsequently, "random" FDs are closed (okay, not that
random since the array is allocated via g_new0(), but hey - FD 0
is still valid FD and might be valuable, actually).

Fixes: 7a38d3946bc1a7ef0206f36dfe3dbf422fb8d578
Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_command.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index be20053c0d..ecfe6020f3 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -8736,6 +8736,8 @@ qemuBuildInterfaceConnect(virDomainObj *vm,
     size_t tapfdSize = net->driver.virtio.queues;
     g_autofree int *tapfd = g_new0(int, tapfdSize + 1);
 
+    memset(tapfd, -1, (tapfdSize + 1) * sizeof(*tapfd));
+
     if (tapfdSize == 0)
         tapfdSize = 1;
 
-- 
2.35.1