livepatch: unpatch all klp_objects if klp_module_coming fails

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.

Reported-by: Miroslav Benes <mbenes@suse.cz>
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index b9628e43c78f60711f8a8c21693aef5c7041f2bb..bf8c8fd72589ddeeae34662a8d76352afa890678 100644 (file)
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -830,6 +830,41 @@ int klp_register_patch(struct klp_patch *patch)
 }
 EXPORT_SYMBOL_GPL(klp_register_patch);
 
+/*
+ * Remove parts of patches that touch a given kernel module. The list of
+ * patches processed might be limited. When limit is NULL, all patches
+ * will be handled.
+ */
+static void klp_cleanup_module_patches_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;
@@ -894,7 +929,7 @@ err:
        pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
                patch->mod->name, obj->mod->name, obj->mod->name);
        mod->klp_alive = false;
-       klp_free_object_loaded(obj);
+       klp_cleanup_module_patches_limited(mod, patch);
        mutex_unlock(&klp_mutex);
 
        return ret;
@@ -902,9 +937,6 @@ err:
 
 void klp_module_going(struct module *mod)
 {
-       struct klp_patch *patch;
-       struct klp_object *obj;
-
        if (WARN_ON(mod->state != MODULE_STATE_GOING &&
                    mod->state != MODULE_STATE_COMING))
                return;
@@ -917,25 +949,7 @@ void klp_module_going(struct module *mod)
         */
        mod->klp_alive = false;
 
-       list_for_each_entry(patch, &klp_patches, list) {
-               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;
-               }
-       }
+       klp_cleanup_module_patches_limited(mod, NULL);
 
        mutex_unlock(&klp_mutex);
 }