[Qemu-devel] [PATCH 1/3] vl.c: Exit QEMU early if no machine is found

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

From: Dunrong Huang <riegamaths@gmail.com>

We check whether the variable machine is NULL or not before accessing
it. If machine is NULL, exit QEMU with an error, this can avoids a
segfault error.

Markus Armbruster <armbru@redhat.com> adds that the segfault can be
reproduced as follows:

  $ qemu-system-xtensa -cpu help

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 vl.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/vl.c b/vl.c
index a4a520f..4871428 100644
--- a/vl.c
+++ b/vl.c
@@ -3204,6 +3204,11 @@ int main(int argc, char **argv, char **envp)
     }
     loc_set_none();
 
+    if (machine == NULL) {
+        fprintf(stderr, "No machine found.\n");
+        exit(1);
+    }
+
     if (machine->hw_version) {
         qemu_set_version(machine->hw_version);
     }
@@ -3246,11 +3251,6 @@ int main(int argc, char **argv, char **envp)
         data_dir = CONFIG_QEMU_DATADIR;
     }
 
-    if (machine == NULL) {
-        fprintf(stderr, "No machine found.\n");
-        exit(1);
-    }
-
     /*
      * Default to max_cpus = smp_cpus, in case the user doesn't
      * specify a max_cpus value.
-- 
1.7.10.4