From 0586576950d5dd34d70cca7adba85e5fb08664f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Wed, 15 May 2019 15:29:25 +0200
Subject: [PATCH] drm/fb-helper: Fix drm_fb_helper_hotplug_event() NULL ptr
argument
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drm_fb_helper_hotplug_event() should tolerate the fb_helper argument being
NULL. Commit 03a9606e7fee ("drm/fb-helper: Avoid race with DRM userspace")
introduced a fb_helper dereference before the NULL check.
Fixup by moving the dereference after the NULL check.
Fixes: 03a9606e7fee ("drm/fb-helper: Avoid race with DRM userspace")
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190515132925.48867-1-noralf@tronnes.org
---
drivers/gpu/drm/drm_fb_helper.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index c259a28522f8e..a52b48fafbd78 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -3031,7 +3031,6 @@ EXPORT_SYMBOL(drm_fb_helper_initial_config);
*/
int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
{
- struct drm_device *dev = fb_helper->dev;
int err = 0;
if (!drm_fbdev_emulation || !fb_helper)
@@ -3044,13 +3043,13 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
return err;
}
- if (!fb_helper->fb || !drm_master_internal_acquire(dev)) {
+ if (!fb_helper->fb || !drm_master_internal_acquire(fb_helper->dev)) {
fb_helper->delayed_hotplug = true;
mutex_unlock(&fb_helper->lock);
return err;
}
- drm_master_internal_release(dev);
+ drm_master_internal_release(fb_helper->dev);
DRM_DEBUG_KMS("\n");
--
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