[PATCH v3 3/9] drm: check for null master in drm_is_current_master_locked
Desmond Cheong Zhi Xi
desmondcheongzx at gmail.com
Wed Aug 18 07:38:18 UTC 2021
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 <desmondcheongzx at gmail.com>
---
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
More information about the dri-devel
mailing list