Re: [Qemu-devel] [PATCH] vl: Avoid crash when -mon is underspecified

[Philippe Mathieu-Daudé]

On 23/10/18 23:35, Eric Blake wrote:

A quick coredump on an incomplete command line:
./x86_64-softmmu/qemu-system-x86_64 -mon mode=control,pretty=on

  #0  0x00007ffff723d9e4 in g_str_hash () at /lib64/libglib-2.0.so.0
  #1  0x00007ffff723ce38 in g_hash_table_lookup () at /lib64/libglib-2.0.so.0
  #2  0x0000555555cc0073 in object_class_property_find (klass=0x5555566a94b0, 
name=0x0, errp=0x0) at qom/object.c:1135
  #3  0x0000555555cc004b in object_class_property_find (klass=0x5555566a9440, 
name=0x0, errp=0x0) at qom/object.c:1129
  #4  0x0000555555cbfe6e in object_property_find (obj=0x5555568348c0, name=0x0, 
errp=0x0) at qom/object.c:1080
  #5  0x0000555555cc183d in object_resolve_path_component 
(parent=0x5555568348c0, part=0x0) at qom/object.c:1762
  #6  0x0000555555d82071 in qemu_chr_find (name=0x0) at chardev/char.c:802
  #7  0x00005555559d77cb in mon_init_func (opaque=0x0, opts=0x5555566b65a0, 
errp=0x0) at vl.c:2291

Fix it to instead fail gracefully.

Signed-off-by: Eric Blake <ebl...@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>

---
  vl.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/vl.c b/vl.c
index 4e25c78bff0..2ed8672eb79 100644
--- a/vl.c
+++ b/vl.c
@@ -2288,6 +2288,10 @@ static int mon_init_func(void *opaque, QemuOpts *opts, 
Error **errp)
      }

      chardev = qemu_opt_get(opts, "chardev");
+    if (!chardev) {
+        error_report("chardev is required");
+        exit(1);
+    }
      chr = qemu_chr_find(chardev);
      if (chr == NULL) {
          error_report("chardev \"%s\" not found", chardev);