From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Wed, 21 Mar 2018 23:12:46 +0200
Subject: drm: Fix uabi regression by allowing garbage mode->type from userspace
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Git-commit: a01c47737a9ca118ab75c6fd6e75739b824de830
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
Apparently xf86-video-vmware leaves the mode->type uninitialized
when feeding the mode to the kernel. Thus we have no choice but
to accept the garbage in. We'll just ignore any of the bits we
don't want. The mode type is just a hint anyway, and more
useful for the kernel->userspace direction.
Reported-by: Thomas Hellstrom <thomas@shipmail.org>
CC: Thomas Hellstrom <thomas@shipmail.org>
Cc: Adam Jackson <ajax@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Fixes: c6ed6dad5cfb ("drm/uapi: Validate the mode flags/type")
References: https://lists.freedesktop.org/archives/dri-devel/2018-March/170213.html
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180321211246.10152-1-ville.syrjala@linux.intel.com
Tested-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/drm_modes.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1611,7 +1611,13 @@ int drm_mode_convert_umode(struct drm_de
out->vscan = in->vscan;
out->vrefresh = in->vrefresh;
out->flags = in->flags;
- out->type = in->type;
+ /*
+ * Old xf86-video-vmware (possibly others too) used to
+ * leave 'type' unititialized. Just ignore any bits we
+ * don't like. It's a just hint after all, and more
+ * useful for the kernel->userspace direction anyway.
+ */
+ out->type = in->type & DRM_MODE_TYPE_ALL;
strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
out->name[DRM_DISPLAY_MODE_LEN-1] = 0;