[Qemu-devel] [PATCH] cpu: Fix crash with empty -cpu option

[Eduardo Habkost]

Fix the following crash:

  $ qemu-system-x86_64 -cpu ''
  qemu-system-x86_64: qom/cpu.c:291: cpu_class_by_name: \
      Assertion `cpu_model && cc->class_by_name' failed.

Regression test script included.

Fixes: commit 99193d8f2ef5 ("cpu: drop unnecessary NULL check and 
cpu_common_class_by_name()")
Signed-off-by: Eduardo Habkost <address@hidden>
---
 exec.c                              |  4 ++++
 tests/acceptance/empty_cpu_model.py | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tests/acceptance/empty_cpu_model.py

diff --git a/exec.c b/exec.c
index 1ca95df9d8..d816b38863 100644
--- a/exec.c
+++ b/exec.c
@@ -999,6 +999,10 @@ const char *parse_cpu_option(MachineState *machine, const 
char *cpu_option)
     const char *cpu_type;
 
     model_pieces = g_strsplit(cpu_option, ",", 2);
+    if (!model_pieces[0]) {
+        error_report("-cpu option cannot be empty");
+        exit(1);
+    }
 
     cc = lookup_cpu_class(model_pieces[0], &error_fatal);
     cpu_type = object_class_get_name(OBJECT_CLASS(cc));
diff --git a/tests/acceptance/empty_cpu_model.py 
b/tests/acceptance/empty_cpu_model.py
new file mode 100644
index 0000000000..3f4f663582
--- /dev/null
+++ b/tests/acceptance/empty_cpu_model.py
@@ -0,0 +1,19 @@
+# Check for crash when using empty -cpu option
+#
+# Copyright (c) 2019 Red Hat, Inc.
+#
+# Author:
+#  Eduardo Habkost <address@hidden>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or
+# later.  See the COPYING file in the top-level directory.
+import subprocess
+from avocado_qemu import Test
+
+class EmptyCPUModel(Test):
+    def test(self):
+        cmd = [self.qemu_bin, '-S', '-display', 'none', '-machine', 'none', 
'-cpu', '']
+        r = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
+        self.assertEquals(r.returncode, 1, "QEMU exit code should be 1")
+        self.assertEquals(r.stdout, b'', "QEMU stdout should be empty")
+        self.assertNotEquals(r.stderr, b'', "QEMU stderr shouldn't be empty")
-- 
2.18.0.rc1.1.g3f1ff2140