From: Noralf Trønnes Date: Wed, 15 May 2019 13:29:25 +0000 (+0200) Subject: drm/fb-helper: Fix drm_fb_helper_hotplug_event() NULL ptr argument X-Git-Tag: v5.15~5932^2~27^2~55 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=0586576950d5dd34d70cca7adba85e5fb08664f7;p=mirror_ubuntu-kernels.git drm/fb-helper: Fix drm_fb_helper_hotplug_event() NULL ptr argument 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 Reported-by: Dan Carpenter Signed-off-by: Noralf Trønnes Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20190515132925.48867-1-noralf@tronnes.org --- diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index c259a28522f8..a52b48fafbd7 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");