The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 622c9a3a7868e1eeca39c55305ca3ebec4742b64 Mon Sep 17 00:00:00 2001 From: Alexander Stein alexander.stein@ew.tq-group.com Date: Wed, 2 Feb 2022 09:17:55 +0100 Subject: [PATCH] drm: mxsfb: Fix NULL pointer dereference

mxsfb should not ever dereference the NULL pointer which drm_atomic_get_new_bridge_state is allowed to return. Assume a fixed format instead.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present") Signed-off-by: Alexander Stein alexander.stein@ew.tq-group.com Signed-off-by: Marek Vasut marex@denx.de Link: https://patchwork.freedesktop.org/patch/msgid/20220202081755.145716-3-alexan...

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c index 0655582ae8ed..4cfb6c001679 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c @@ -361,7 +361,11 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc, bridge_state = drm_atomic_get_new_bridge_state(state, mxsfb->bridge); - bus_format = bridge_state->input_bus_cfg.format; + if (!bridge_state) + bus_format = MEDIA_BUS_FMT_FIXED; + else + bus_format = bridge_state->input_bus_cfg.format; + if (bus_format == MEDIA_BUS_FMT_FIXED) { dev_warn_once(drm->dev, "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"