drm: add a locked version of drm_is_current_master
While checking the master status of the DRM file in drm_is_current_master(), the device's master mutex should be held. Without the mutex, the pointer fpriv->master may be freed concurrently by another process calling drm_setmaster_ioctl(). This could lead to use-after-free errors when the pointer is subsequently dereferenced in drm_lease_owner(). The callers of drm_is_current_master() from drm_auth.c hold the device's master mutex, but external callers do not. Hence, we implement drm_is_current_master_locked() to be used within drm_auth.c, and modify drm_is_current_master() to grab the device's master mutex before checking the master status. Reported-by:Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by:
Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> Reviewed-by:
Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210712043508.11584-4-desmondcheongzx@gmail.com
parent
5eff9585
Please register or sign in to comment