Re: [PATCH] chardev: fix segfault in finalize

[Marc-André Lureau]

Hi

On Thu, Aug 25, 2022 at 9:02 PM Maksim Davydov <davydov-max@yandex-team.ru> wrote:

If finalize chardev-msmouse or chardev-wctable is called immediately after
init it cases QEMU to crash with segfault. This happens because of
QTAILQ_REMOVE in qemu_input_handler_unregister tries to dereference
NULL pointer.
For instance, this error can be reproduced via `qom-list-properties`
command.

Signed-off-by: Maksim Davydov <davydov-max@yandex-team.ru>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

 

---
 chardev/msmouse.c  | 4 +++-
 chardev/wctablet.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/chardev/msmouse.c b/chardev/msmouse.c
index eb9231dcdb..2cc1b16561 100644
--- a/chardev/msmouse.c
+++ b/chardev/msmouse.c
@@ -146,7 +146,9 @@ static void char_msmouse_finalize(Object *obj)
 {
     MouseChardev *mouse = MOUSE_CHARDEV(obj);

-    qemu_input_handler_unregister(mouse->hs);
+    if (mouse->hs) {
+        qemu_input_handler_unregister(mouse->hs);
+    }
 }

 static QemuInputHandler msmouse_handler = {
diff --git a/chardev/wctablet.c b/chardev/wctablet.c
index e8b292c43c..43bdf6b608 100644
--- a/chardev/wctablet.c
+++ b/chardev/wctablet.c
@@ -319,7 +319,9 @@ static void wctablet_chr_finalize(Object *obj)
 {
     TabletChardev *tablet = WCTABLET_CHARDEV(obj);

-    qemu_input_handler_unregister(tablet->hs);
+    if (tablet->hs) {
+        qemu_input_handler_unregister(tablet->hs);
+    }
 }

 static void wctablet_chr_open(Chardev *chr,
--
2.25.1

--

Marc-André Lureau