This series fixes a number of use-after-frees in nouveau's postclose() handler. It was discovered by pointing IGT's core_hotunplug tests at a nouveau device, but the steps to reproduce it are simple:
1. Open the device file 2. Unbind the driver or remove the device 3. Close the file opened in step 1.
During the device removal, the nouveau_drm structure is de-allocated, but is dereferenced in the postclose() handler.
One obvious solution is to ensure all the operations in the postclose() handler are valid by extending the lifetime of the nouveau_drm structure. This is possible with the new devm_drm_dev_alloc() interface, but the change is somewhat invasive so I thought it best to submit that work separately.
Instead, we make use of the drm_dev_unplug() API, clean up all clients in the device removal call, and check to make sure the device has not been unplugged in the postclose() handler. While this does not enable hot-unplug support for nouveau, it's enough to avoid crashing the kernel and leads to all the core_hotunplug tests to pass.
Jeremy Cline (3): drm/nouveau: use drm_dev_unplug() during device removal drm/nouveau: Add a dedicated mutex for the clients list drm/nouveau: clean up all clients on device removal
drivers/gpu/drm/nouveau/nouveau_drm.c | 39 +++++++++++++++++++++++---- drivers/gpu/drm/nouveau/nouveau_drv.h | 5 ++++ 2 files changed, 39 insertions(+), 5 deletions(-)