[PATCH v3 3/9] drm: check for null master in drm_is_current_master_locked
From: Desmond Cheong Zhi Xi <hidden>
Date: 2021-08-18 07:40:46
Also in:
dri-devel, intel-gfx, linux-media, lkml
Subsystem:
drm drivers, drm drivers and misc gpu patches, the rest · Maintainers:
David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Linus Torvalds
There is a window after calling drm_master_release, and before a file is freed, where drm_file can have is_master set to true, but both the drm_file and drm_device have no master. This could result in wrongly approving permissions in drm_is_current_master_locked. Add a check that fpriv->master is non-NULl to guard against this scenario. Signed-off-by: Desmond Cheong Zhi Xi <redacted> --- drivers/gpu/drm/drm_auth.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 8c0e0dba1611..f9267b21556e 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c@@ -66,7 +66,8 @@ static bool drm_is_current_master_locked(struct drm_file *fpriv) lockdep_assert_once(lockdep_is_held(&fpriv->minor->dev->master_lookup_lock) || lockdep_is_held(&fpriv->minor->dev->master_mutex)); - return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master; + return (fpriv->is_master && fpriv->master && + drm_lease_owner(fpriv->master) == fpriv->minor->dev->master); } /**
--
2.25.1
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