Xwayland's `xwl_destroy_window()` invokes `xwl_present_cleanup()` before the common `DestroyWindow()`.
But then `DestroyWindow()` calls `present_destroy_window()` which will possibly end up in `xwl_present_abort_vblank()` which will try to access data that was previously freed by `xwl_present_cleanup()`: Invalid read of size 8 at 0x434184: xwl_present_abort_vblank (xwayland-present.c:378) by 0x53785B: present_wnmd_abort_vblank (present_wnmd.c:651) by 0x53695A: present_free_window_vblank (present_screen.c:87) by 0x53695A: present_destroy_window (present_screen.c:152) by 0x42A90D: xwl_destroy_window (xwayland.c:653) by 0x584298: compDestroyWindow (compwindow.c:613) by 0x53CEE3: damageDestroyWindow (damage.c:1570) by 0x4F1BB8: DbeDestroyWindow (dbe.c:1326) by 0x46F7F6: FreeWindowResources (window.c:1031) by 0x472847: DeleteWindow (window.c:1099) by 0x46B54C: doFreeResource (resource.c:880) by 0x46C706: FreeClientResources (resource.c:1146) by 0x446ADE: CloseDownClient (dispatch.c:3473) Address 0x182abde0 is 80 bytes inside a block of size 112 free'd at 0x4C2FDAC: free (vg_replace_malloc.c:530) by 0x42A937: xwl_destroy_window (xwayland.c:647) by 0x584298: compDestroyWindow (compwindow.c:613) by 0x53CEE3: damageDestroyWindow (damage.c:1570) by 0x4F1BB8: DbeDestroyWindow (dbe.c:1326) by 0x46F7F6: FreeWindowResources (window.c:1031) by 0x472847: DeleteWindow (window.c:1099) by 0x46B54C: doFreeResource (resource.c:880) by 0x46C706: FreeClientResources (resource.c:1146) by 0x446ADE: CloseDownClient (dispatch.c:3473) by 0x446DA5: ProcKillClient (dispatch.c:3279) by 0x4476AF: Dispatch (dispatch.c:479) Block was alloc'd at at 0x4C30B06: calloc (vg_replace_malloc.c:711) by 0x433F46: xwl_present_window_get_priv (xwayland-present.c:54) by 0x434228: xwl_present_get_crtc (xwayland-present.c:302) by 0x539728: proc_present_query_capabilities (present_request.c:227) by 0x4476AF: Dispatch (dispatch.c:479) by 0x44B5B5: dix_main (main.c:276) by 0x75F611A: (below main) (libc-start.c:308) This is because `xwl_present_cleanup()` frees the memory but does not remove it from the window's privates, and `xwl_present_abort_vblank()` will still find it and hence try to access that freed memory... Clear `xwl_present_cleanup()` after `DestroyWindow()` so that `xwl_present_abort_vblank()` can still access valid memory before it's freed. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1616269 Signed-off-by: Olivier Fourdan <ofour...@redhat.com> --- hw/xwayland/xwayland-present.c | 5 +++++ hw/xwayland/xwayland.c | 10 +++++----- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/hw/xwayland/xwayland-present.c b/hw/xwayland/xwayland-present.c index 81e0eb9ce..316e04443 100644 --- a/hw/xwayland/xwayland-present.c +++ b/hw/xwayland/xwayland-present.c @@ -147,6 +147,11 @@ xwl_present_cleanup(WindowPtr window) /* Clear timer */ xwl_present_free_timer(xwl_present_window); + /* Remove from privates so we don't try to access it later */ + dixSetPrivate(&window->devPrivates, + &xwl_present_window_private_key, + NULL); + free(xwl_present_window); } diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c index 96b4db18c..63d69fb3a 100644 --- a/hw/xwayland/xwayland.c +++ b/hw/xwayland/xwayland.c @@ -642,11 +642,6 @@ xwl_destroy_window(WindowPtr window) struct xwl_screen *xwl_screen = xwl_screen_get(screen); Bool ret; -#ifdef GLAMOR_HAS_GBM - if (xwl_screen->present) - xwl_present_cleanup(window); -#endif - screen->DestroyWindow = xwl_screen->DestroyWindow; if (screen->DestroyWindow) @@ -657,6 +652,11 @@ xwl_destroy_window(WindowPtr window) xwl_screen->DestroyWindow = screen->DestroyWindow; screen->DestroyWindow = xwl_destroy_window; +#ifdef GLAMOR_HAS_GBM + if (xwl_screen->present) + xwl_present_cleanup(window); +#endif + return ret; } -- 2.17.1 _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: https://lists.x.org/mailman/listinfo/xorg-devel