drm/nouveau/mmu: qualify vmm during dtor

commit 15516bf9abaa41421a6ded79a5a2fee86f9594e5 upstream.

If the BAR initialization failed it may leave the vmm structure in an
unitialized state, leading to a null-pointer-dereference when the vmm is
dereferenced during teardown.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sushma Kalakota <sushmax.kalakota@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index 7459def..5f8b8b3 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -1423,7 +1423,7 @@ nvkm_vmm_get(struct nvkm_vmm *vmm, u8 page, u64 size, struct nvkm_vma **pvma)
 void
 nvkm_vmm_part(struct nvkm_vmm *vmm, struct nvkm_memory *inst)
 {
-       if (inst && vmm->func->part) {
+       if (inst && vmm && vmm->func->part) {
                mutex_lock(&vmm->mutex);
                vmm->func->part(vmm, inst);
                mutex_unlock(&vmm->mutex);