Maciej W. Rozycki 1235485c63 vgacon: Propagate console boot parameters before calling `vc_resize' ... commit 3dfac26e2e upstream. Fix a division by zero in `vgacon_resize' with a backtrace like: vgacon_resize vc_do_resize vgacon_init do_bind_con_driver do_unbind_con_driver fbcon_fb_unbind do_unregister_framebuffer do_register_framebuffer register_framebuffer __drm_fb_helper_initial_config_and_unlock drm_helper_hpd_irq_event dw_hdmi_irq irq_thread kthread caused by `c->vc_cell_height' not having been initialized. This has only started to trigger with commit 860dafa902 ("vt: Fix character height handling with VT_RESIZEX"), however the ultimate offender is commit 50ec42edd9 ("[PATCH] Detaching fbcon: fix vgacon to allow retaking of the console"). Said commit has added a call to `vc_resize' whenever `vgacon_init' is called with the `init' argument set to 0, which did not happen before. And the call is made before a key vgacon boot parameter retrieved in `vgacon_startup' has been propagated in `vgacon_init' for `vc_resize' to use to the console structure being worked on. Previously the parameter was `c->vc_font.height' and now it is `c->vc_cell_height'. In this particular scenario the registration of fbcon has failed and vt resorts to vgacon. Now fbcon does have initialized `c->vc_font.height' somehow, unlike `c->vc_cell_height', which is why this code did not crash before, but either way the boot parameters should have been copied to the console structure ahead of the call to `vc_resize' rather than afterwards, so that first the call has a chance to use them and second they do not change the console structure to something possibly different from what was used by `vc_resize'. Move the propagation of the vgacon boot parameters ahead of the call to `vc_resize' then. Adjust the comment accordingly. Fixes: 50ec42edd9 ("[PATCH] Detaching fbcon: fix vgacon to allow retaking of the console") Cc: stable@vger.kernel.org # v2.6.18+ Reported-by: Wim Osterholt <wim@djo.tudelft.nl> Reported-by: Pavel V. Panteleev <panteleev_p@mcst.ru> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2110252317110.58149@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2021-12-08 09:03:28 +01:00
..
dummycon.c
Kconfig	parisc/sticon: Add user font support	2020-10-15 08:12:59 +02:00
Makefile
mdacon.c	vt: use newly defined CUR_* macros	2020-06-24 17:08:33 +02:00
newport_con.c	TTY/Serial patches for 5.10-rc1	2020-10-14 16:05:52 -07:00
sticon.c	parisc/sticon: fix reverse colors	2021-11-26 10:39:20 +01:00
sticore.c	parisc/sticon: Add user font support	2020-10-15 08:12:59 +02:00
vgacon.c	vgacon: Propagate console boot parameters before calling `vc_resize'	2021-12-08 09:03:28 +01:00