chardev: fix qemu_chr_open_fd() being called with fd=-1

The "file" chardev may call qemu_chr_open_fd() with fd_in=-1. This may
cause invalid system calls, as the QIOChannel is assumed to be properly
initialized later on.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 17 insertions, 9 deletions

diff --git a/chardev/char-fd.c b/chardev/char-fd.c
index 743d398..c11b103 100644
--- a/chardev/char-fd.c
+++ b/chardev/char-fd.c
@@ -39,6 +39,10 @@ static int fd_chr_write(Chardev *chr, const uint8_t *buf, int len)
 {
     FDChardev *s = FD_CHARDEV(chr);
 
+    if (!s->ioc_out) {
+        return -1;
+    }
+
     return io_channel_send(s->ioc_out, buf, len);
 }
 
@@ -209,15 +213,19 @@ void qemu_chr_open_fd(Chardev *chr,
     FDChardev *s = FD_CHARDEV(chr);
     char *name;
 
-    s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
-    name = g_strdup_printf("chardev-file-in-%s", chr->label);
-    qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
-    g_free(name);
-    s->ioc_out = QIO_CHANNEL(qio_channel_file_new_fd(fd_out));
-    name = g_strdup_printf("chardev-file-out-%s", chr->label);
-    qio_channel_set_name(QIO_CHANNEL(s->ioc_out), name);
-    g_free(name);
-    qemu_set_nonblock(fd_out);
+    if (fd_in >= 0) {
+        s->ioc_in = QIO_CHANNEL(qio_channel_file_new_fd(fd_in));
+        name = g_strdup_printf("chardev-file-in-%s", chr->label);
+        qio_channel_set_name(QIO_CHANNEL(s->ioc_in), name);
+        g_free(name);
+    }
+    if (fd_out >= 0) {
+        s->ioc_out = QIO_CHANNEL(qio_channel_file_new_fd(fd_out));
+        name = g_strdup_printf("chardev-file-out-%s", chr->label);
+        qio_channel_set_name(QIO_CHANNEL(s->ioc_out), name);
+        g_free(name);
+        qemu_set_nonblock(fd_out);
+    }
 }
 
 static void char_fd_class_init(ObjectClass *oc, void *data)