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core: Avoid generating XEvent from uninitialized data

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The uninitialized fields in this event causes use of uninitialised
data as seen in valgrind:

==71864== Syscall param writev(vector[0]) points to uninitialised byte(s)
==71864==    at 0x5026EBD: __writev (writev.c:26)
==71864==    by 0x5026EBD: writev (writev.c:24)
==71864==    by 0x6482A3B: UnknownInlinedFun (xcb_conn.c:296)
==71864==    by 0x6482A3B: _xcb_conn_wait.part.0 (xcb_conn.c:551)
==71864==    by 0x6482BAF: UnknownInlinedFun (xcb_out.c:469)
==71864==    by 0x6482BAF: _xcb_out_send (xcb_out.c:470)
==71864==    by 0x6483DD7: UnknownInlinedFun (xcb_out.c:416)
==71864==    by 0x6483DD7: xcb_writev (xcb_out.c:409)
==71864==    by 0x53B79B4: _XSend (xcb_io.c:587)
==71864==    by 0x53BBF38: _XReply (xcb_io.c:679)
==71864==    by 0x53AFFC9: XQueryTree (QuTree.c:47)
==71864==    by 0x4982A5F: query_xserver_stack (stack-tracker.c:508)
==71864==    by 0x4EA1F5F: g_closure_invoke (gclosure.c:832)
==71864==    by 0x4ECFD45: signal_emit_unlocked_R.isra.0 (gsignal.c:3796)
==71864==    by 0x4EC0129: g_signal_emit_valist (gsignal.c:3549)
==71864==    by 0x4EC03B2: g_signal_emit (gsignal.c:3606)
==71864==  Address 0x287d5900 is 32 bytes inside a block of size 16,384 alloc'd
==71864==    at 0x4849444: calloc (vg_replace_malloc.c:1340)
==71864==    by 0x53A5FE8: XOpenDisplay (OpenDis.c:240)
==71864==    by 0x6100E3C: _gdk_x11_display_open (gdkdisplay-x11.c:1565)
==71864==    by 0x60CF675: gdk_display_manager_open_display (gdkdisplaymanager.c:462)
==71864==    by 0x49D59F1: open_gdk_display (meta-x11-display.c:1041)
==71864==    by 0x49D5D64: meta_x11_display_new (meta-x11-display.c:1156)
==71864==    by 0x49564AD: meta_display_init_x11_finish (display.c:743)
==71864==    by 0x495679D: on_x11_initialized (display.c:818)
==71864==    by 0x4D67558: g_task_return_now (gtask.c:1232)
==71864==    by 0x4D67782: UnknownInlinedFun (gtask.c:1301)
==71864==    by 0x4D67782: g_task_return (gtask.c:1258)
==71864==    by 0x495663C: on_xserver_started (display.c:788)
==71864==    by 0x4D67558: g_task_return_now (gtask.c:1232)
==71864==  Uninitialised value was created by a stack allocation
==71864==    at 0x49D4A59: take_manager_selection (meta-x11-display.c:640)
==71864==

To fix this, fully initialize the event struct before sending it.

Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2535
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2724>
This commit is contained in:
Bram Stolk 2022-11-29 10:00:33 -08:00 committed by Marge Bot
parent 20bf7f5ceb
commit 7a103bbfe9
1 changed files with 1 additions and 1 deletions
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2
src/x11/meta-x11-display.c
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@ -688,7 +688,7 @@ take_manager_selection (MetaX11Display *x11_display,
{ {
/* Send client message indicating that we are now the selection owner */ /* Send client message indicating that we are now the selection owner */
XClientMessageEvent ev; XClientMessageEvent ev = { 0, };
ev.type = ClientMessage; ev.type = ClientMessage;
ev.window = xroot; ev.window = xroot;