Commit 572994bf18ff ("drm/ast: Zero is missing in detect function") prevents some systems from booting. Seen on Supermicro Super Server/X10SRL-F, BIOS 3.3 10/28/2020 . There's further a bug that results in

KASAN: use-after-free in enqueue_timer+0x4f/0x1e0

which is also triggered by commit 572994bf18ff ("drm/ast: Zero is missing in detect function").

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: 572994bf18ff ("drm/ast: Zero is missing in detect function") Reported-by: Chuck Lever III chuck.lever@oracle.com Reported-by: Kim Phillips kim.phillips@amd.com Cc: Ainux.Wang ainux.wang@gmail.com Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Dave Airlie airlied@redhat.com Cc: dri-devel@lists.freedesktop.org Link: https://lore.kernel.org/dri-devel/A194B6CE-AF77-422D-A92F-292ABD83BCCE@oracl... --- drivers/gpu/drm/ast/ast_mode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c index 6bfaefa01818..ea64944ad4ca 100644 --- a/drivers/gpu/drm/ast/ast_mode.c +++ b/drivers/gpu/drm/ast/ast_mode.c @@ -1306,7 +1306,7 @@ static enum drm_connector_status ast_connector_detect(struct drm_connector int r;

r = ast_get_modes(connector); - if (r <= 0) + if (r < 0) return connector_status_disconnected;

return connector_status_connected;