drm/xe: defer free of NVM auxiliary container to device release callback

Do not kfree the intel_dg_nvm_dev in xe_nvm_fini() right after
auxiliary_device_delete/uninit. The auxiliary_device embeds the
device/kobject (and its name); freeing it too early can race
with asynchronous device_del/udev processing and cause a use-after-free.

Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
Fixes: c28bfb1 ("drm/xe/nvm: add on-die non-volatile memory device")
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250911052823.226696-1-nitin.r.gote@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Author: NitinGote

drivers/gpu/drm/xe/xe_nvm.c

@@ -35,6 +35,10 @@ static const struct intel_dg_nvm_region regions[INTEL_DG_NVM_REGIONS] = {
 
 static void xe_nvm_release_dev(struct device *dev)
 {
+	struct auxiliary_device *aux = container_of(dev, struct auxiliary_device, dev);
+	struct intel_dg_nvm_dev *nvm = container_of(aux, struct intel_dg_nvm_dev, aux_dev);
+
+	kfree(nvm);
 }
 
 static bool xe_nvm_non_posted_erase(struct xe_device *xe)
@@ -162,6 +166,5 @@ void xe_nvm_fini(struct xe_device *xe)
 
 	auxiliary_device_delete(&nvm->aux_dev);
 	auxiliary_device_uninit(&nvm->aux_dev);
-	kfree(nvm);
 	xe->nvm = NULL;
 }