Commit ef8daf8e authored by Joe Lawrence's avatar Joe Lawrence Committed by Jiri Kosina
Browse files

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: default avatarMiroslav Benes <mbenes@suse.cz>
Suggested-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent dcba7108

kernel/livepatch/core.c

+37 −23
Original line number Diff line number Diff line
@@ -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);

}

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