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| author | Lyude <cpaul@redhat.com> | 2016-05-12 10:56:59 -0400 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-06-15 09:32:15 +0200 |
| commit | 2408770d2b5cad295e386333a22dcf10ad3a546f (patch) | |
| tree | 815017de6e8bc327071c13f08bc8274a5d018839 | |
| parent | ab548aa85b0d2d9a7339f745aca979b2852d49fc (diff) | |
| download | lwn-2408770d2b5cad295e386333a22dcf10ad3a546f.tar.gz lwn-2408770d2b5cad295e386333a22dcf10ad3a546f.zip | |
drm/fb_helper: Fix references to dev->mode_config.num_connector
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@redhat.com>
[danvet: Clarify why we need this. Also remove the now unused "dev"
local variable to appease gcc.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1463065021-18280-3-git-send-email-cpaul@redhat.com
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/gpu/drm/drm_fb_helper.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 49557c957be8..1965b8963606 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -1359,7 +1359,6 @@ static int drm_pick_crtcs(struct drm_fb_helper *fb_helper, 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; @@ -1380,7 +1379,7 @@ static int drm_pick_crtcs(struct drm_fb_helper *fb_helper, 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; @@ -1427,7 +1426,7 @@ static int drm_pick_crtcs(struct drm_fb_helper *fb_helper, best_crtc = crtc; best_score = score; memcpy(best_crtcs, crtcs, - dev->mode_config.num_connector * + fb_helper->connector_count * sizeof(struct drm_fb_helper_crtc *)); } } |