Fix read from uninitialized dataHEADmaster

  Syscall param writev(vector[0]) points to uninitialised byte(s)
     at 0x4B836C0: writev (writev.c:26)
     by 0x4C74FBF: ??? (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
     by 0x4C753B0: xcb_writev (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
     by 0x48B2A24: _XSend (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
     by 0x48B3088: _XReply (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
     by 0x48AE6FE: XSync (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
     by 0x11C523: HandleEnterNotify (events.c:2112)
     by 0x117847: DispatchEvent (events.c:335)
     by 0x117921: HandleEvents (events.c:363)
     by 0x12FCBD: main (twm.c:648)
   Address 0x5036874 is 148 bytes inside a block of size 16,384 alloc'd
     at 0x48459F3: calloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
     by 0x48A23AA: XOpenDisplay (in /usr/lib/x86_64-linux-gnu/libX11.so.6.4.0)
     by 0x49E5A12: XtOpenDisplay (in /usr/lib/x86_64-linux-gnu/libXt.so.6.0.0)
     by 0x12EB45: main (twm.c:319)
   Uninitialised value was created by a stack allocation
     at 0x12828E: send_clientmessage (menus.c:2861)

Signed-off-by: Tim Wiederhake <twied@gmx.net>
Part-of: <https://gitlab.freedesktop.org/xorg/app/twm/-/merge_requests/29>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/menus.c b/src/menus.c
index 41f5bad..7814771 100644
--- a/src/menus.c
+++ b/src/menus.c
@@ -2860,6 +2860,7 @@ static void
 send_clientmessage(Window w, Atom a, Time timestamp)
 {
     XClientMessageEvent ev;
+    memset(&ev, '\0', sizeof(ev));
 
     ev.type = ClientMessage;
     ev.window = w;