On 2018-09-05 10:35 a.m., Olivier Fourdan wrote: > 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.
This last paragraph doesn't seem to match the rest of the patch. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ 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