From 0c8e6ed85810e96d84173a52d628863802a78d82 Mon Sep 17 00:00:00 2001
From: Daniel Stone <daniels@collabora.com>
Date: Fri, 7 Apr 2017 14:27:58 +0100
Subject: [PATCH xserver] modesetting: Set correct DRM event context version

DRM_EVENT_CONTEXT_VERSION is the latest context version supported by
whatever version of libdrm is present. modesetting was blindly asserting
it supported whatever version that may be, even if it actually didn't.

With libdrm 2.4.78, setting a higher context version than 2 will attempt
to call the page_flip_handler2 vfunc if it was non-NULL, which being a
random chunk of stack memory, it might well have been.

Set the version as 2, which should be bumped only with the appropriate
version checks.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Daniel Stone <daniels@collabora.com>
---
 hw/xfree86/drivers/modesetting/vblank.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/xfree86/drivers/modesetting/vblank.c b/hw/xfree86/drivers/modesetting/vblank.c
index 04a8952..8682f4d 100644
--- a/hw/xfree86/drivers/modesetting/vblank.c
+++ b/hw/xfree86/drivers/modesetting/vblank.c
@@ -402,7 +402,7 @@ ms_vblank_screen_init(ScreenPtr screen)
     modesettingEntPtr ms_ent = ms_ent_priv(scrn);
     xorg_list_init(&ms_drm_queue);
 
-    ms->event_context.version = DRM_EVENT_CONTEXT_VERSION;
+    ms->event_context.version = 2;
     ms->event_context.vblank_handler = ms_drm_handler;
     ms->event_context.page_flip_handler = ms_drm_handler;
 
-- 
2.9.3