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 3.14-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-3.14 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 @@ -1347,7 +1347,6 @@ 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; struct drm_connector_helper_funcs *connector_funcs; struct drm_encoder *encoder; @@ -1366,7 +1365,7 @@ 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; @@ -1412,7 +1411,7 @@ 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-3.14/drm-fb_helper-fix-references-to-dev-mode_config.num_connector.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html