linux-kernel - [PATCH] drm/crtc: fix uninitialized variable use even harder

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date: Mon, 12 Feb 2024 13:55:34 -0800
From: Rob Clark <robdclark@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: Rob Clark <robdclark@...omium.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Jani Nikula <jani.nikula@...el.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] drm/crtc: fix uninitialized variable use even harder

From: Rob Clark <robdclark@...omium.org>

DRM_MODESET_LOCK_ALL_BEGIN() has a hidden trap-door (aka retry loop),
which means we can't rely too much on variable initializers.

Fixes: 6e455f5dcdd1 ("drm/crtc: fix uninitialized variable use")
Signed-off-by: Rob Clark <robdclark@...omium.org>
---
I have mixed feelings about DRM_MODESET_LOCK_ALL_BEGIN() (and friends)
magic.  On one hand it simplifies the deadlock/back dance.  OTOH it
conceals a nasty sharp edge.  Maybe it is better to have the complicated
restart path a bit more explicit, like it was originally.

 drivers/gpu/drm/drm_crtc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index cb90e70d85e8..65f9f66933bb 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -904,6 +904,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 	connector_set = NULL;
 	fb = NULL;
 	mode = NULL;
+	num_connectors = 0;
 
 	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
 
-- 
2.43.0