When an incoming module is considered for livepatching by klp_module_coming(), it iterates over multiple patches and multiple
kernel objects in this order:
list_for_each_entry(patch, &klp_patches, list) {
klp_for_each_object(patch, obj) {
which means that if one of the kernel objects fails to patch, klp_module_coming()'s error path needs to unpatch and cleanup any kernel objects that were already patched by a previous patch.
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index b9628e43c78f..3d457e0bbe26 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -830,6 +830,42 @@ int klp_register_patch(struct klp_patch *patch)
}
EXPORT_SYMBOL_GPL(klp_register_patch);
+/*
+ * Revert patches (up to a given limit) to objects belonging to a given
+ * kernel module. After unpatching such objects, the function also
+ * frees them. When limit is NULL, all patches to the given module will
+ * be reverted.
+ */
+static void klp_cleanup_module_objects_limited(struct module *mod,
+ struct klp_patch *limit)
+{
+ struct klp_patch *patch;
+ struct klp_object *obj;
+
+ list_for_each_entry(patch, &klp_patches, list) {
+ if (patch == limit)
+ break;
+
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+ continue;
+
+ /*
+ * Only unpatch the module if the patch is enabled or
+ * is in transition.
+ */
+ if (patch->enabled || patch == klp_transition_patch) { + pr_notice("reverting patch '%s' on unloading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+ klp_unpatch_object(obj);
+ }
+
+ klp_free_object_loaded(obj);
+ break;
+ }
+ }
+}
+
int klp_module_coming(struct module *mod)
{
int ret;
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