This is a note to let you know that I've just added the patch titled
drm/fb_helper: Fix references to dev->mode_config.num_connector
to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-fb_helper-fix-references-to-dev-mode_config.num_connector.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 255f0e7c418ad95a4baeda017ae6182ba9b3c423 Mon Sep 17 00:00:00 2001
From: Lyude <cpaul@xxxxxxxxxx>
Date: Thu, 12 May 2016 10:56:59 -0400
Subject: drm/fb_helper: Fix references to dev->mode_config.num_connector
From: Lyude <cpaul@xxxxxxxxxx>
commit 255f0e7c418ad95a4baeda017ae6182ba9b3c423 upstream.
During boot, MST hotplugs are generally expected (even if no physical
hotplugging occurs) and result in DRM's connector topology changing.
This means that using num_connector from the current mode configuration
can lead to the number of connectors changing under us. This can lead to
some nasty scenarios in fbcon:
- We allocate an array to the size of dev->mode_config.num_connectors.
- MST hotplug occurs, dev->mode_config.num_connectors gets incremented.
- We try to loop through each element in the array using the new value
of dev->mode_config.num_connectors, and end up going out of bounds
since dev->mode_config.num_connectors is now larger then the array we
allocated.
fb_helper->connector_count however, will always remain consistent while
we do a modeset in fb_helper.
Note: This is just polish for 4.7, Dave Airlie's drm_connector
refcounting fixed these bugs for real. But it's good enough duct-tape
for stable kernel backporting, since backporting the refcounting
changes is way too invasive.
Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
[danvet: Clarify why we need this. Also remove the now unused "dev"
local variable to appease gcc.]
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1463065021-18280-3-git-send-email-cpaul@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_fb_helper.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1895,7 +1895,6 @@ static int drm_pick_crtcs(struct drm_fb_
int n, int width, int height)
{
int c, o;
- struct drm_device *dev = fb_helper->dev;
struct drm_connector *connector;
const struct drm_connector_helper_funcs *connector_funcs;
struct drm_encoder *encoder;
@@ -1914,7 +1913,7 @@ static int drm_pick_crtcs(struct drm_fb_
if (modes[n] == NULL)
return best_score;
- crtcs = kzalloc(dev->mode_config.num_connector *
+ crtcs = kzalloc(fb_helper->connector_count *
sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
if (!crtcs)
return best_score;
@@ -1960,7 +1959,7 @@ static int drm_pick_crtcs(struct drm_fb_
if (score > best_score) {
best_score = score;
memcpy(best_crtcs, crtcs,
- dev->mode_config.num_connector *
+ fb_helper->connector_count *
sizeof(struct drm_fb_helper_crtc *));
}
}
Patches currently in stable-queue which might be from cpaul@xxxxxxxxxx are
queue-4.6/drm-i915-fbdev-fix-num_connector-references-in-intel_fb_initial_config.patch
queue-4.6/drm-i915-psr-try-to-program-link-training-times-correctly.patch
queue-4.6/drm-fb_helper-fix-references-to-dev-mode_config.num_connector.patch
queue-4.6/drm-i915-discard-previous-atomic-state-on-resume-if-connectors-change.patch
queue-4.6/drm-atomic-verify-connector-funcs-null-when-clearing-states.patch
--
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